86 GN popping breaking up problem

[buickturboman]

86 GN that seems to idle ok but breaks up and pops back through the MAF when you try to rev up the engine even a little it seems to hesitate and break up really bad in addition when this occurs the factory boost gauge will jump up to 5-8 psi good fuel pressure, has a rich exhasut smell, all readings on direct scan seem ok-New coil pack, replaced MAF, EGR, sensor, plugs, wires,swapped out computers, plugged and unplugged direct scan (not trouble coding at all). Just replaced PCV grommet and fuel injector O rings (Had a vacuum leak sound which the O rings fixed). Don't seem to have a problem with battey cables as other people had. Any ideas guys.

 

[Murt TTA]

did you test / replace the ignition module that the coil packs sit on? Sounds like something ignition related. Did u replace the MAF w/ a delco unit?

 

[buickturboman]

Module not replaced. MAF I believe is remanuf AC Delco. I still have original I can swap out but problem existed before I got new MAF- reason I got the rebuilt one.
IS there a way to test a module?

 

[buickturboman]

Module is about the only thing not replaced and not cheap to buy to try to correct prob. Don't think there are diagnostic tools available to find the overall problem. If one to rest module, would like to know.

 

[87granny]

Does it idle rough then smooth out when you bring the throttle up slowly my module was bad but no poping only had spark on 4 cylinders

 

[turbo39151]

Hows the CAT?

 

[buickturboman]

Seems to be just the opposite, seems to idle somewhat fine but breaks up when throttle up. Occassionally stalls out.

 

[buickturboman]

Punched out cat.... Exhaust system all 3". Car been in garage for a few years and occassionally taken around the block. Ran mid 11's when first put it up.

 

[87NAT]

What do the new plugs look like? Fouled out?

Caspers makes an ignition/coil pack tester. I bought one and it is amazing..you can actually see each coil towers spark thickness to see if one is weak or not.

 

[Electrajim]

Caspers makes an ignition/coil pack tester. I bought one and it is amazing..you can actually see each coil towers spark thickness to see if one is weak or not.

EXCELLENT must have product IMO!!
This thing will tell the story with the ignition/coil pack. Trust me.
IT's cool to watch and listen to also.
Just watch your fingers!!

In my experience, the ignition on these cars must be GM parts or forget it.
I don't care how close a replacement looks, fits, or costs.
Word.

Your problem sounds like it's ignition.
Try tracking your electrical system output too when you bring up the throttle. Make sure it's not falling off.

Reman MAF's are always hit and miss too.
See if you can borrow a known good working unit.

What are your DS readings?

ElectraJim

 

[buickturboman]

I remember these testers now, seen them in the catalogs for years. Yeah they are about $125. Time to get one. Thanks for the post.

 

[Murt TTA]

u might want to check your engine grounds also, but if you could get the tester or get a known working coil pack/ module u could rule that out..

 

[Electrajim]

u might want to check your engine grounds also, but if you could get the tester or get a known working coil pack/ module u could rule that out..

Good idea.
If you order that tester from Caspers, they also make a "ground stretcher" system that can supplement the factory grounds. It's a little tough to hookup, but the design seems reasonable.

ElectraJim

 

[godwingn87]

u might want to check your engine grounds also, but if you could get the tester or get a known working coil pack/ module u could rule that out..

+1 on the grounds- I had the same problem, tested with the Caspers coil pack tester and the center pack would work great until I turned the knob up. It would give out on the higher end. Turned out just to be loose grounds. One way you can test is to connect a wire to the metal base of the coil pack to the firewall. There's already a ground behind it that would make a good place to connect. Once I found out how critical the ground was I went ahead and added an additional ground to the pack just to be on the safe side. Good luck on finding the problem

 

[87NAT]

I have the ground relocation kit also. I took some 10 guage wire and grounded the coil/ign brackets to this also. I also ran 4 guage grounds from negative battery to frame and body. Cant have enough good grounds on these cars.

 

[turbo39151]

I have to disagree with the coil pack tester idea. While it may work on a visual level, it is not a tool that gives you any real information. Can you tell by "eyeballing it"- what the numbers are from one spark to the other? Nope! I bought one of these tools because I had heard they were a "must have". I sent it back. It was useless IMHO.

As for your problem, it sounds like maybe the injectors are crapping out. What is your fuel pressure reading? How old are the injectors? One of my cars had this same issue, I swapped the injectors and plugs (because I fouled them) and the car ran much better. If it smells rich, it is possible you have fouled the plugs as well.
Just a thought.

 

[Electrajim]

I have to disagree with the coil pack tester idea. While it may work on a visual level, it is not a tool that gives you any real information. Can you tell by "eyeballing it"- what the numbers are from one spark to the other? Nope! I bought one of these tools because I had heard they were a "must have". I sent it back. It was useless IMHO.

As for your problem, it sounds like maybe the injectors are crapping out. What is your fuel pressure reading? How old are the injectors? One of my cars had this same issue, I swapped the injectors and plugs (because I fouled them) and the car ran much better. If it smells rich, it is possible you have fouled the plugs as well.
Just a thought.

Can you recommend a procedure to test the coil pack and module?
How did you test your injector$ before you knew you needed to replace them?
I was totally lucky with my injectors. My stockers went over over 200K miles before I replaced them for an upgrade.

Just curious,

ElectraJim

 

[turbo39151]

I have not yet been able to find a procedure to test an ignition module or coil pack. Best I have been able to do is use one that works off of one of my other TR's or a friend's TR and make the comparisons. The few times I thought my coil pack was bad, it turned out to be something completely different.

As for the injectors, it was hardly scientific. The car ran like crap and always smelled rich. The injectors were stock and I figured that maybe 20 year old injectors might need replacing and by the condition the car was in when I got it, they probably had not been changed/cleaned/maintained. Additionally, I am always looking for an excuse to upgrade. So, I shopped on this board and found a deal on a set of MSD 50's and ordered a chip from TT. The way I figure, why limit the potential of the car or increase the possibility of a problem by running older stock parts that were not really intended for what we expect out of our cars. I personally run 24# of boost on the street and I am not concerned about the fuel system at all- because it's all new and upgraded.

If nothing else, I eliminated a potential problem and upgraded my combo without "needlessly" throwing money at the car. I hate repairs, I love upgrades...

 

[ngnowner]

coil test

It's easy to test the coil with a digital votlmeter. Set to 20K ohms, test each of the 3 towers, doesn't matter positive vs. negative lead just test resistance across each of the 3 towers. Sould be between 11K-13K ohms. My car "popped" under full power and at midrange, checked the coil and the 1-4 tower was full resistance (infinity). Replaced the coil and no more intake pop. The ignition module is an amplifier, you may be able to see difference in spark intensity with the caspers tester but first make sure coil resistance is within spec. If not replace the coil with a know good one.

 

[buickturboman]

Good point. I did check this . Thanks.