91 3.4 Not firing on 2 and 5

[BNaylor]

GM specs on ignition wires for DIS systems is no more than 600 ohms per foot. Not all aftermarket ignition wires meet that spec but the OE GM/Packard and the recommended AC Delco replacements do.

[19jettadad97]

Originally Posted by BNaylor

Yeah I know I am a pompous "a" hole.

Damn Bob, that's the most truthful thing I've heard since I came to this site. Just kidding!!!!
Anyway, Tim, no I didn't ohm the wires but no matter which wires I put on 2 or 5 I get the same results. The wires are AC Delco. Also I didn't use a spark tester, I go old school, plug in end of wire arched to the cam cover.
I had a similar problem last year a couple months after the stealership changed the timing belt and ALL pulleys and everything. Turned out the timing belt tensioner was a defect. So they replaced the belt and tensioner free but now it's been almost a year. That's why it makes me think it might be that again.

[tblake]

Pull all 6 wires off your igniton module and have an assistant crank the motor over for just a few seconds. between each of the oil towers you will see the sparks jumping across. Make sure all 3 are able to arch across and be a nice blue hot spark. If they look good then your problem is elsewhere.

Have you ohm checked each coils primary and secondary side yet? Bob's the go-to guy for the specs on them too. I'm not good at remembering.

[19jettadad97]

Originally Posted by BNaylor

However, before replacing the ECU module I would check the ignition control circuits wiring point to point between the ICM and ECU using a reliable wiring diagram and to the crank position sensors (24X and 3X). Concentrating on IC and Bypass mode wiring. Plus inspect the back of the harmonic balancer and how the 24X crank sensor is mounted or aligned.

I think this is my next step. I'm gonna try changing the CPS (doesn't cost much) and the wire from the CPS to the ICM. I can't do it till next weekend maybe. If that don't work it's going to the stealership. I'm thinking more and more it's that damn tensioner. If so, it's gonna have to wait for spring. I lost my garage in the divorce. It's the only thing I miss.

[tblake]

I just dont think that the belt tensioner can cause weak spark on only one coil pack.

[tblake]

Hey, maybe this guy will ship. THen you will have a spair for test purposes....

http://minneapolis.craigslist.org/pts/1031460919.html

[19jettadad97]

Originally Posted by tblake

I just dont think that the belt tensioner can cause weak spark on only one coil pack.

Yeah, I don't get it either but last year when this happened I changed everything and then decided to bring it in. They changed the timing belt tensioner, and the belt, and it was fine afterward. I don't see why they would say it was that seeing how THEY were footin' the bill. By the time I brought it in it was only running on 2 cylinders. Oh well, I'll just bring it in and see what they say, I'm tired of racking my brain on this.

Thanks for ALL the info. IF I get it fixed, I'll let you know.

[richtazz]

Originally Posted by BNaylor

I guess that was a no go. Good thing you didn't go to Las Vegas to bet but good advice considering at times you have to replace the components to rule them out. ....... Yeah I know I am a pompous "a" hole.

I recall the early 90s GPs were notorious for flaky ECU modules. Since the ECU is mounted on the passenger side front strut tower and was subject to the weather elements, corrosion and wiring issues as a result. So that is a possibility.


However, before replacing the ECU module I would check the ignition control circuits wiring point to point between the ICM and ECU using a reliable wiring diagram and to the crank position sensors (24X and 3X). Concentrating on IC and Bypass mode wiring. Plus inspect the back of the harmonic balancer and how the 24X crank sensor is mounted or aligned. Thats all I can think of without the car being in front of me.

That's the exact reason I don't bother going to Vegas Bob.

The 91 3.4 Vin-X only has one CKPS in the back of the block, so don't bother looking for the one behind the balancer as there isn't one. I would inspect the wiring between the CKPS and the ICM first, as it runs awful close to the passenger side CV axle and the harmonic balancer as it wraps under the front of the engine and could be damaged. If the wiring checks out, I would concentrate on the ECM as well, as they are a high failure part as Bob mentioned due to being mounted under the hood and exposed to the elements. I would also do a cmpression test (no easy task on a 3.4 DOHC) as these motors are known for blowing head gaskets and burning valves.

[19jettadad97]

Originally Posted by richtazz

That's the exact reason I don't bother going to Vegas Bob.

The 91 3.4 Vin-X only has one CKPS in the back of the block, so don't bother looking for the one behind the balancer as there isn't one. I would inspect the wiring between the CKPS and the ICM first, as it runs awful close to the passenger side CV axle and the harmonic balancer as it wraps under the front of the engine and could be damaged. If the wiring checks out, I would concentrate on the ECM as well, as they are a high failure part as Bob mentioned due to being mounted under the hood and exposed to the elements. I would also do a cmpression test (no easy task on a 3.4 DOHC) as these motors are known for blowing head gaskets and burning valves.

YEah I know, that's why I listen to EVERYONE first. It's on the bottom back of the block, next to the knock sensor. That's the LAST thing I am gonna do then, I'm done, it's going in.

Now that I think of it, when I changed the oil sensor I might have tugged on the wires to hard. I think they are in the same harness. Man, that would really piss me off to think I, me, as experienced as I am, did this myself. I'll check on it next weekend. It's back to cold rainy weather again.

[tblake]

Originally Posted by 19jettadad97

I'll check on it next weekend. It's back to cold rainy weather again.

Do you live in the MidWest?

Every time you mention weather, we are getting the same exact stuff here.

[19jettadad97]

Originally Posted by tblake

Do you live in the MidWest?

Every time you mention weather, we are getting the same exact stuff here.

No, but we do get the same weather within a couple days. Yours comes this way. This damn New England weather really sucks, one day 60* the next 12 inches of snow. Gotta love it!!!!

[tblake]

Isnt it something?