Once I traveled to a nearby town with a fellow instructor in an attempt to recruit some high school students from that school in that town. He and I taught different disciplines, but we were recruiting for our entire division. He was a passionate, vociferous gentleman of great dignity and really enjoyed presenting before groups of students.
Every group of students has a different personality, as peculiar as that might sound to those who don’t teach. And one group of boys looked like they were so totally disinterested in everything. Their eyes were on their desks, or looking around at others, and their faces were masks of utter boredom. I stepped forward and put my hand on my colleague’s shoulder to pause his presentation.
He is a well-muscled, broad-shouldered man with big hands who shaves his head and dresses like a CEO when he’s not teaching his technical trade. He paused with a pained expression on his face – not so much because I asked him to give me a moment as he was that they weren’t hearing anything he had to say about his program or technical education. He stepped back with his big, callused hands clasped in front of him while I addressed the group.
“How many of you boys know about that ‘tough man’ contest the comes around every so often where guys sign up for a ten-thousand-dollar prize if they can beat every other guy in the contest one-on-one?” All their hands shot up. I pointed at my fellow instructor. “He entered that contest and won that ten thousand dollars.” I stepped back and motioned for my fellow instructor to continue.
From that point on, their eyes were on him. That one tidbit totally changed their perspective and from what we could tell, they heard every single word he said for the rest of his presentation.
Three jobs where almost nothing went right but we won the fight anyway.
We run through quite a bit of work, and the ones we really learn from are the hardest ones to figure out. We also learn from our mistakes, and yes, I know I’m the only one who ever makes a mistake (NOT). Students sometimes disassemble things they didn’t need to because of inexperience, and other times they’ll have to backtrack because of some important part that was left out during assembly. Then there are those times they’ll approach a big or complicated job without even looking at the shop manual, and they’ll put themselves in a bind.
For one example among many, I had a guy replacing the engine in a 2005 Kia Sportage a few years ago, and he just plowed into it without doing any reading at all. Well, when he got the engine disconnected from the transaxle, he discovered that there wasn’t enough room to get the engine out of there without bringing the transaxle with it. Had he simply perused the information system verbiage before beginning that task, it would have gone a lot smoother.
Then there are times when following the shop manual is a really bad idea because some of the information in the shop manual is SOS, i.e., “Stuck On Stupid,” as if the procedures were written by a desk-bound service engineer who never actually laid eyes on the vehicle. Surely I’m not the only one who has ever run afoul of such misinformation! We did work on a Kia Sedona that provides a perfect example of the misinformation malady, meaning we would have been better off NOT to have even checked the shop manual R&R procedures.
SOS Number 1
The Sedona came to me from a family member who had noticed compressor noise that was so bad he couldn’t stand to operate the A/C unless it was really hot outside. The A/C was cooling just fine, but that noisy compressor needed to be gone, and so I put a couple of my people to work on it. We’d replace the compressor, the drier, and the expansion valve. Knowing the Asian penchant for stuffing the expansion valve in the evaporator case, I wasn’t surprised to read in Alldata that the evaporator case needed to be removed in order to replace this TXV, and when we took those published procedures for gospel, we made a wrong turn. Most shop manual publishers get their information from the manufacturer’s shop manuals (with permission), but some of the Asian manuals leave a lot to be desired, and this one was no exception.
In strict obedience to the Alldata service procedure on this platform, they removed the instrument panel, which, by the way, on one of these Sedonas, is no small feat if you haven’t done one. I usually stay out of the way when it seems like my folks are making progress and following procedure, but as I walked by this van about the time they got the panel out, I mentioned the fact that those “block” type expansion valves are usually just inside the engine compartment rather than in the evaporator case (except on Toyotas), and that’s when I peered into the dark recesses of the engine compartment on the passenger side and found that this van was no exception to that rule of domestic normalcy. The entire dash removal was totally unnecessary, because the valve was right there where it was supposed to be. Oh, well. They needed to jank a dash and put it back anyway. So be it. The end of the story was that the dash went back in well and the compressor is now cool and quiet.
SOS Number Two
The second SOS job we’ll peruse is a cute but intrinsically boring little 2007 Cobalt. The first time we saw this one, it was running awful. The girl who drives it is a gentle soul who wouldn’t speak a harsh word to or about anybody, but in this case, she had good cause to complain, but she told her story with a smile. She had gone to a shop in a nearby town a few days earlier to have them look at the car because it was running so poorly at idle, and she said the shop replaced the spark plugs (that’s all they put on the bill) and charged her $500, but the car still ran like a three-legged dog. Well, when she asked why the bill was so high, their reply was that half of it was labor. She didn’t even ask why the car still ran so poorly, she just drove away and came to us. She was “Stuck On Sweet.” Too sweet, if you ask me!
What my guy found was a sizeable split in a hose, and when he fixed that vacuum leak, the little car idled smoothly, but when we drove it, the right front wheel bearing was quite literally so loud it sounded like a two cycle engine running at wide open throttle in the right front floorboard while you were driving along. The owner didn’t even mention that totally off-the-charts bearing noise, and if the shop that replaced those very expensive spark plugs had done a verify-the-repair test drive they would certainly have heard it. We got the green light to replace that right front bearing and after we did, the Cobalt drove like a little piece of heaven compared to what she had been experiencing before.
About three weeks later, she called me again and said she had run over something in the road she thought was a stick, only it turned out to be a piece of rebar that created a massive breach in that aluminum oil pan, and all the engine’s slippery juice found its way onto the highway in very short order. She indicated that she hadn’t driven it far after the impact, but when we got the oil pan off, it turned out that one of the rods had been hot enough to change color – it was deathly gray.
The local chain parts store is typically pretty good about getting replacement powertrain components through LKQ. I used to deal directly with the local LKQ depot, but it has moved. So I had them price me out a replacement engine, and the owner gave the go-ahead. My guys got the engine out of the Cobalt with the powertrain lift, then they rolled it over to the area where we do our disassembly/reassembly and they disconnected the engine from the sub frame and the transaxle, then removed it and put it on an old tire while the new engine was headed our way. That’s where the SOS syndrome kicked in at the parts store.
Two weeks went by – the engine should have already arrived. I called every day to ask about the ETA, and my industrial sales parts guy kept saying he was expecting it “any day.” Well, it turned out that the LKQ truck had dropped it off at the parts store when the industrial sales guy was absent, then another truck came in with pallet-loads of parts, and the second-string crew stacked a bunch of pallets in front of the engine, which had been shoved against the wall. It sat there for ten days before anybody figured out what happened.
When the engine arrived, we pulled the flywheel off to check the rear main seal and removed the valve cover to check for sludge. The rear seal was seeping, but the innards of the power plant were sludge-free. They popped the seal out and we ordered a replacement. When it arrived, one of the guys came carrying the new seal holding it up next to the old seal he had picked up from the table and it was obviously a different size.
Now WE were in SOS mode, only we didn’t know it. I called the parts guy, thinking the engine we had received was a newer model or something, because there were other differences that had to be addressed between the old and new engines and other parts that needed transferring. The parts guy was bewildered, and when our personal cloud of SOS smoke cleared, we discovered that my guys had picked up a rear main seal we had replaced from a 91 F150 for comparison to the replacement seal and that the first seal had been the right one all along. We lost another day or two sorting that nonsense out.
We finally got the Cobalt back together (we installed the other shop’s $250 set of spark plugs in the replacement engine for good measure), filled it up with oil and coolant and watched the ECT with the EASE Wireless Vehicle Interface while the thermostat opened and closed and the fan cycled, test drove it a few times, and she was back on the road.
SOS Number Three
This one was one part SOS and one part ground breaking experience, which is never a good combination but always interesting. The car was an ancient 1997 Mazda 626 V6 that was featured in a previous article – they had dragged it out of a barn and we had cleaned the fuel tank and replaced the fuel pump to get it going. Later we had replaced a weak ignition coil because it was sputtering and misfiring under load. They drove it for a year or two and then it started making some funky rattling noises and they wanted that checked.
My substitute was running the shop while I was at KC Vision, and the students just knew they needed to remove the engine oil pan, which was totally unnecessary, but the sub let them do it. In the process of checking the bottom end, one of the guys managed to do the not-too-smart SOS thing and turn the engine backwards, which caused it to jump a few timing belt teeth. I figured this out when I returned, because there was a big half-inch drive ratchet hanging on the crank bolt and it was set to turn the engine counter-clockwise.
I had them yank the timing cover to check the marks, and sure enough, the engine was out of time. But while we were there, we discovered the reason for that rattling noise, which I recognized, but they didn’t. That self-contained hydraulic timing belt tensioner was all squishy and needed replacing. Well, we replaced the tensioner, and put a timing belt kit on it along with a water pump, and we put a set of serpentine belts on as well, reinstalled the oil pan, and poured in new oil with a new filter and new coolant in the jacket.
We got it running without a rattle, but it had an annoying misfire, and when we investigated that, we found a split plug wire insulator and most of the spark plug wells nearly full of engine oil. The customer wanted that fixed too, and so the intake was removed, the valve cover gaskets, spark plugs, and wires were replaced, and since the starter tended to click a few times before it would spin most of the time, the starter was replaced as well at the customer’s request. This bill was climbing really fast on a car that might be worth 500 bucks sitting by the road with a for sale sign on it.
Well, that’s when SOS kicked in again. The car wouldn’t start after the work was done, and the guy working on it said he couldn’t hear the injectors but that it had fuel pressure – long story short (too late), the O-scope showed injector pulse, so he had taken a wrong turn thinking the injectors weren’t operating. After the guys all left one day, I found that he had mixed up the banks when installing the plug wires, and I fixed that to get it started, but the starter was spinning so slowly it would barely crank the engine, and so we got it off and I bench tested it to find it spinning very slowly and with great effort.
A second replacement starter was sent, and it was bench tested as well – it spun aggressively and powerfully in the vise, and so we installed it, but on the car, it would spin slower than normal, even with good strong battery power. A voltage drop test showed some ground-side loss, and so we replaced the ground side cable, connecting it directly to the upper starter bolt, but the starter still spun slower than normal.
This was getting weird. Sometimes the starter wouldn’t spin at all, and during one of those times, my guy used a low-impedance test light to check for power at the solenoid terminal with it disconnected from its spade and got really good power. What the heck was going on here? SOS, I figured.
I took my pocket screwdriver and shorted the starter’s hot terminal to the solenoid spade and the starter spun like brand new – the conclusion of this matter was that the ignition switch was dropping enough voltage with current flowing to the solenoid so that the solenoid windings weren’t getting enough current to jerk that big copper washer against the internal contacts. That test light that burned brightly was a deceptive test, because it doesn’t pull as many amps as the solenoid. A meter and a high impedance test light are pretty useless in situations like this too. Best to use a headlight bulb to check for adequate amperage.
I was going to demonstrate this to some of the other guys so they’d get a better understanding of voltage drop and what it means, but when I did the pocket screwdriver thing that copper washer welded itself to the contacts inside the solenoid and the starter wouldn’t stop spinning until I removed the battery cable. The solenoid’s washer needs to pop hard against its contacts like a hybrid vehicle system’s battery contactors, and it had been compromised by not smacking the contacts hard enough too many times. We had to install yet another starter and an ignition switch to finish the job.
Doing one right…
A Buick Rendezvous that had been to two other shops that had given up on it for no fuel pump operation and no-start, we found this:
The end of the story is that, like the vehicles we have to work on, we don’t always operate at our full potential. Further, we’re all human, and sometimes things come at us so fast that we make snap decisions, taking things at face value, and draw false conclusions that lead to wrong turns. But we don’t have to stay Stuck On Stupid, even if we’re having a bad day. And as I tell my guys and gals, any time you get so sick of a car that you want it gone worse than you want it fixed right, you’re out of touch with what it means to be a good technician. We can stay in the fight, fix it right, and win if we will. R.W.M.
I don’t know if this repair was attempted by the customer, a buddy of his, or a fly-by-night independent. Most shops see situations like this fairly regularly. The owner of the car turned the key on this Jeep one morning and the engine spun and spun. He opened the hood. He looked around under there, hoping to find something that might have come loose, but everything looked like it did the last time he looked. Maybe he called his wrench-wise neighbor. Maybe he dragged his Jeep to Jack’s friendly fix-it-while-U-wait Auto Shop. Quite a few dollars went whistling over the parts counter and the Jeep was still sitting there grinding away with no hint of any life of its own.
Whoever it was that did the work on this Jeep knew enough to be mildly dangerous. Spark plugs, wires, and a distributor cap don’t really hurt anything, especially on a high mileage engine. The Crank sensor is a fairly good guess, but no cigar. The “Pickup Coil” (cam sensor, actually) in the distributor can cause a no-start, but it didn’t do the job either. Finally, some wrecker driver’s phone rang the Jeep wound up at our shop.
Ignition System Basics Revisited
When I discovered the wonderful world under the hood working with my dad around 1970, we had contact points, a condenser and an ignition coil, and we were all very happy. Then Chrysler Engineers sent shockwaves through repair shops all over the country by making “Electronic Ignition” a household word in 1972.
There was “pickup coil” in the distributor which sent an analog signal to a mysterious box on the firewall called an “Ignition Module,” which, in turn, used a transistor to do what the points once did, repeatedly saturating the primary windings on the ignition coil with a magnetic field, collapsing the field, and producing a high voltage in the secondary coil windings.
This secondary high voltage was discharged through the coil wire to the center post on the distributor cap and then delivered to center of the ever-spinning rotor button. The spark traveled through the metal strip on the rotor and jumped out the tip, which happened to be in the vicinity of the spark plug terminal that needed the spark. In order for things to work right, the spark had (and has) to be delivered to each cylinder at the right time.
(see my YouTube video on Ignition System Evolution at this link:
The spark plug wires have to be in the right order on the distributor cap or the engine will pop and snort, either kicking back or belching flame under the hood or with a great boom through the exhaust. Most of us have seen muffler shops reap a handsome profit from this frightening scenario.
Fine-tuning the timing was done by turning the distributor, which, in the old days, changed the time when the points opened and closed, and in the newer days, accomplished the same thing with the signal delivered by the pickup coil to the module. Nowadays, even when a vehicle has a distributor, turning it this way and that sometimes only makes the engine run worse, because in many cases the “pickup coil” in the distributor has a different job than it once did.
On this Jeep, the signal the PCM uses to fire the coil comes from the Crank sensor. There are three sets of four notches on the six-cylinder flywheel (V8’s have 8 notches spaced at 45 degrees, but that’s a different story). The Cam Sensor in the distributor (known as a “pickup coil” to Jack’s auto repair) tells the PCM which cylinder is #1, and the trailing edge of notch number four in each group of notches on the flywheel (read by the Crank Sensor) tells the PCM that the cylinder in question is at 4 degrees Before Top Dead Center (BTDC). Since it knows where #1 and #6 are based on Cam sensor input, it can use the Crank Sensor input figure out which cylinder is which to synchronize injector pulse. To be honest, this info isn’t anything you’ll use very much in the field, because you can’t make adjustments to change it anyway.. Suffice it to say that, (generally speaking) when a crank sensor is present, the ignition timing can’t be adjusted by turning the distributor, even if it has one.
Thus turning the distributor on the 4.0L Jeep just fouls up the rotor alignment. Keep this in mind, because it’s an important part of the story. Earlier Jeeps (87-90) with that old bulletproof Bendix fuel injection system have a similar Crank/Cam sensor setup, but the flywheel sensor ring on those units has narrow notches all the way around the ring except three wide ones that are spaced 120 degrees apart. The principle was the same, but the older Jeep would start with the cam sensor unplugged. The 91/up Jeep 4.0L engines will run if the cam sensor is unplugged after the engine is started but they won’t start with it unplugged.
Under the Hood
This ‘93 Jeep was sitting out behind the shop where the wrecker driver had deposited it. Turning the key produced the sound of a strong battery and a healthy starter, but no fire in any of the holes. Popping the hood and looking around, I didn’t see anything out of the ordinary under there, but based on what “Jack’s” had replaced with his shotgun, I already had an idea what the problem was.
The first thing I wanted to do was check for spark at the ignition coil, (it’s best not to check fuel pressure first, or you could start a fire) and just as I suspected, there was no spark at all. Some folks like to check for spark at the plugs, but I start at the coil. Obviously, if there isn’t any spark at the coil, there won’t be any at the plugs.
It looked like somebody had checked for spark at the plugs, found none, and replaced the plugs and wires. When they still had no spark, they replaced the Crank Sensor, and when that didn’t produce any results, they replaced the “Pickup Coil.” This is a natural progression for a shotgunner. In some cases, they meet with success using this method, but it generally costs more in parts than it needs to.
In some cases, spark will be present at the coil tower, but it’ll be too weak to coax any fire into the cylinders, where the atmosphere is compressed and rather unfriendly to being punctured by a spark. The trick here is understanding how weak is too weak. I’ve seen more than one seasoned mechanic who was body slammed by a no-start and a weak spark. If the spark won’t jump but about a quarter of an inch, the engine probably won’t start, even though some shop manuals use that distance for a good measure.
A half-inch jump is pretty good, but if it won’t jump any farther than that, I’ve seen hard cold starting as a result. While it can be tough on the ignition components to stretch the spark to the point where it looks for somewhere else to go, I like to see at least three quarters of an inch of bright blue lightning, and a comfortably loud pop.
(Important author’s note: Most of the old round oil-filled ignition coils produced from 40,000 to 60,000 volts. When the newer coils started appearing in the mid-seventies (like GM’s HEI unit), that voltage jumped to around 80,000 volts. With the advent of distributorless ignition, coil voltages have increased to over 100,000 volts. It’s not good to horse around with that sort of voltage. If it runs through your chest cavity the right way it can stop your heart, so don’t play tricks on your buddies with these systems and don’t take unnecessary chances yourself to prove how macho you are. A heart attack could ruin your whole day. It’s best to use the plastic pliers you bought from the tool guy for this exercise or perhaps one of those handy adjustable spark testers.)
Finding the Problem
Scan tool trouble codes are usually helpful, but they can be misleading. In this case, Chrysler’s DRBII threw me a curve, and if I hadn’t been familiar with an old Jeep recall program I might have been sidetracked. The DRBII readout said “FUEL PUMP RESISTOR BYPASS RELAY CIRCUIT FAULT.”
That trouble code message rang a bell in my mental hard drive. I remembered that we had been required to disable that relay on Cherokees in the mid-‘90s, but as I write this I can’t remember why we had to do it. At any rate, if you happen to run across this code on an early ‘90’s Cherokee, don’t spend a lot of time chasing it.
Bringing up the Inputs and Outputs on the DRBII screen, I found that the Jeep’s ASD (Automatic Shutdown) relay was operating normally. This is the relay Chrysler uses to fire up the ignition coil, the alternator field, and the injectors. If for some reason the ASD relay fails to power all that stuff up, the unit obviously won’t start. The orange wire feeding the Hall Effect Crank and Cam sensors receives an eight-volt feed from the PCM, and if that orange feed wire is chafing against ground somewhere no signals will be sent from the Crank and Cam sensors to the PCM. In this case, the 8 volts were there, because my DRB showed the Cam and Crank sensors to be operating as expected.
At this point, since I had my crosshairs on the lack of ignition spark, I could have checked the primary lead on the coil with a test light while spinning the engine to see if a signal was present, but instead I plugged in a substitute coil I keep on hand and received the healthy blue pop you see in the photo above. Everything seemed fine until I popped the coil wire on the new coil and tried to start the engine…
Pop, Snort, Start-and Die
The engine immediately gave its best attempt at firing up, but bumped and snorted, then yanked itself to a stop rather abruptly, as if a pair of spark plug wires had been crossed. When Jack’s (or whoever it was that worked on it) had replaced the “pickup coil”, they had put the distributor back in place a tooth out of phase. This distributor has a set of ears (see photo) that keep would-be do-it-yourselfers from trying to turn the distributor and set the timing. In this case, the pop-snort condition was present because the rotor alignment was out of sync and the spark was jumping to the wrong posts and firing the wrong cylinders.
In order to untangle this hopscotch and get things back in line, you simply bring the timing notch up on TDC (#1 compression stroke!), then use a distributor cap that has been cut out to reveal the number one firing post.
The distributor turns clockwise, so set the distributor so that the rotor has just passed the number one post.
In the late ‘80’s, Jeep actually told us to hacksaw the ears off the base of the distributor and turn it until the rotor was in this position if we had an annoying skip or surge at cruise. If you set the rotor pointing straight at the post, you’ll get hard starting and an annoying surge at highway cruise because when the PCM advances the timing beyond a certain point, some or all of the spark will jump back and hit the previous post in the cap instead of the right one. Some old timers might remember the days of Ford’s EEC III system where rotor alignment had to be set with a special tool for the same reason.
It only took a few minutes to set the rotor alignment and we had main engine burn on the Jeep once again.
Digging out the birdshot is rewarding when you finally hear an engine start up and run right.