AGreen

My family bought this car brand new. 1992 Oldsmobile Achieva SCX. 1 of ~1500 made. 190HP 2.3 liter 4 cylinder with a 5 speed manual.

Now it's my brother's car, and it crapped out. No spark, so I replaced the spark module. Now it's firing on 2 cylinders only. Now, cylinders 1 & 4 are companion cylinders, meaning they share the same coil. The same goes for cylinders 2 & 3. However, the car's only running off of cylinders 2 & 4.

I have good compression in each cylinder, timing, spark at each cylinder, injector pulse, pulled the injector rail to verify all injectors firing. I've replaced the spark module twice, checked the coils, replaced the computer, and verified the crank sensor signal.

Someone please shoot me some advice!

DTN

Ok, first, verify that you do or do not have spark coming from those cylinders. Hook up the spark plug to the spark plug wire and then touch the edge of the spark plug to ground somewhere. You should be able to see it spark.

Next check for continuity in the spark plug wires. Check to make sure that the ohms readings are alright and check by spraying the spark plug wires down at night, lightly, with some water to see if they spark. Also, make sure there's no bare metal.

Your car has a wasted spark system. The electricity jumps from ground in the motor, through 1 spark plug, through the plug wire, to the coil, to the other wire, to the 2nd spark plug and back to ground in the motor. If that loop is broken, then you will definitely have a problem.

The spark plug coil has basically a transformer in it, 2 coils close together. If for some reason the primary coil cannot excite the secondary coil, then the same problems could happen.

Jed118

The good old Quad4... in non-counterbalanced guise! Good on you for not chucking it!

Check the condition of the tower's insulation. There's also the possibility that the spark isn't making it all the way to the cylinder. This happened to me and I replaced the wires, plugs, points even, before a friend noticed that the spark is jumping around the cap. The cuplrit: a cracked dist cap (I know you don't have one, but check the casing nonetheless) allowing the spark to go all over the place between wires and the car's ground, especially when it was humid outside.

Since you said 2 and 4 work, we can see that the coil is firing when it needs to. Try this: take out all the plug wires from the head, stick a screwdriver in the end of the plug and bring the metal close to ground (or use the aforementioned spark plug method). Crank. Note the results. Cross 1 and 4 at the coil and 2 and 3 on the other coil and crank again. If there is a difference between which cylinder fires, (pair-based order: swap 1 and 4 and previously 1 was firing and now 4 is instead - vice versa with 2 and 3) there's something wrong with the coil. If you get the same results, it's the plug wires.

If you DO get it running, pay attention to the timing belts on these motors. One's failure was the reason I got a free 1994 Acheiva - S. I thought nothing of it until the cheapest head I could price out was $900... plus timing belt and tensionner... yeah the entire car got swapped for a Mk II Jetta's 2.0 GTi upper intake and throttle body at a wreckers.

Solid motor otherwise, especially from those years when GM didn't care that it rattled around and N/H/V wasn't an issue.

AGreen

I have spark at all cylinders. That's the problem!! I'm not sure what you mean about crossing the wires, since this car has one of those engine covers that has the coils, module, and plug boots (no wires) between it and the head. I tested for spark by unbolting the cover and using my old tiburon's wires to go between the cover (known as the IDI tower) and the spark plugs, then placing an inline spark tester between each wire.

What I'm sure is happening is that it's firing the first signal for each revolution, but not the second. The first one, for instance, would fire #2 on its compression stroke, and #3 at the same time, only on its exhaust stroke. Now, it needs to fire #3 on it's compression stroke, and #2 on the exhaust. The second signal is somehow not getting sent. So that would probably explain why I'm getting spark on all 4 cylinders, but running on 2.

The way the spark is created is this: Crank sensor sends signal to the module. Module creates a 1x and 2x reference signal based on the crank rotation. 1x is a square wave pulse at crank speed, and 2x is the same, just twice the engine speed. I just got both a logic probe and a multimeter that has frequency. I hooked the multimeter up to the output of the spark module, and checked frequency of the 1x and 2x reference signals. I have both.

Still trucking on sigh.gif

Jed118

OK this may be irrelevant, but I had a 1989 Pontiac 6000 which acted in the following manner:

Start car cold, OK
Drive for 10 mins turn off OK
Drive for more than 10 mins, will not restart till engine cools (about 1 hour)

There was a crank position sensor mounted to a thin plate inside the block somewhere that when the engine heated up, the plate would move away and stop giving the signal. I don't know why it didn't shut the car off, I mean I drove it to Kingston from Toronto and no issues at all (had to fill up with the car on) but it just would not restart until the engine cooled.

I eventually got sick of it and pawned it for a TV.

In any case, I have access to a quad4 motor out of a grand prix. It isn't mine but I'm sure I could pick a couple small peices off it.

Why not search around for a Quad4 website? I know there's one for the 60 degree V6's, (http://www.60degreev6.com/) I'm sure there's one for the Quad4

tib _500

ok easy fix replace the plastic tower piece that all the boots connect to. this fixes the problem 99% of the time with the quad four.

AGreen

all of you have good advice, but it won't work. The plastic insulator for the IDI tower is brand new. Costs about $80 from GM, but since my brother was a parts guy there, we got it for $40. The crank signal thing sounds interesting, but the reluctor wheel is literally inside the engine, with the crank sensor bolted in the block.

I'm probably going to have to find that Quad4 specific website. I just like posting here because 1) I know the people here and 2) I know the people here aren't idiots. There are alot more cars with quad4's out there than there are tiburons, and there's a lot of people on this website with great knowledge. That means there's more idiots with Quad4's than idiots with Tiburons!

It's like the Rx7 website I'm a part of. Unfortunately, Rx7's are abused by 16 year olds who think they know everything about that car. Whenever I ask a specific question (similar to the one asked here) all I ever get is the generic autozone answer. You know.... "did you check yer oxygen sensors?? durka-durr??"

At this point, I'm almost convinced I've received the wrong module twice in a row. It has to be. I'm getting all the signals where I'm supposed to, but I haven't tested the signal coming out of the module. If that's jacked up, the I know it's the wrong one. Otherwise, I'll just have to call in a priest for an exorcism.

tib _500

has it had any timing work done to it? my dad has done three diferent ones that have jumped time by 1-3 teeth. most of the time, after it has receved a timing job and ran great, then a month or so after...runs like crap.

DTN

You said you have spark, so you actually pulled the spark plugs and visually checked for a spark signal? If you did, then why are we talking about the plastic piece in the first place? It's a straight up fuel/compression/timing problem.

AGreen

Plastic piece? The only reason I mentioned that damn thing is because I KNOW it's not the problem! lmao.gif

I thought about what tib_500 said and pulled the timing chain cover this morning. Timing is still spot on. Back to the drawing board.

DTN, here's a schematic for you. This is porn for you electronics techs....



Let me point out that IN NO FREAKIN' WAY ARE CYLINDERS 2 & 4 RELATED!!!!!! This is why it's pissing me off so badly!

aargh4.gif