Weak spark cause a lean condition????

[Amelio]

I am still trying to figure out the issue with the car, I was talking about this under another thread regarding testing fuel pimp output but I know think my fueling is ok. the problem is anything over 16psi or better the car just noses over like you shut the key off, my initial thought was a fueling issue but I have plenty of fuel under WOT my o2's are 780 or so.... I am now wondering if my spark is falling off under higher boost. Up to 15psi the car runs great and pulls hard but over that and it is done, I have zero knock so I am thinking coil pack or module.

I pulled my plugs the other day and they do look a little on the lean side as far as color. Would a weak spark generate a lean look on the plug? I would think a weak spark would give me a rich condition due to unburned fuel in the cylinder.

I did have a burned ground wire that had corrosion, could that bad ground have caused either my coil pack or module to go? Just trying to figure out all possible solutions before I start changing parts.

By the way the car acts it is something that is affecting all cylinders at once, as soon as it hits 16psi the car is done and it just sounds like pistons moving air with no spark , of course as soon as this happens I lift so trying to get a good grasp on what is happening is a little difficult.

Ideas please........

 

[Waco84GN]

What amazes me is no knock...

You are not showing any knock? If it is leaning out to the point of slowing the motor down it seems that there should be some knock. Is there a possibility that the knock sensor or wiring is faulty? Also the EST module could be going crazy and doing bad things with the timing. Any kind of data logs would show a change in commanded ECM timing.

I think race gas or octane boosters will leave a residue on spark plugs and o2 sensors making them appear white.

Jerry jr.

 

[1quick6]

I agree with the above. If the plugs are tan/off white, you are normal. If they are white crusty looking deposits, it can be from off the shelf additives.

I'd test your coil pack with an ohm meter. You should see 11-13k resistance between the paired towers, front to back.

 

[Mad_Trbo]

Caspers Electronic Ignition tester

It does sound like it could be an ignition problem. As the cylinder builds more pressure with boost it becomes more difficult for the plug to light.

I would recommend for anyone with these cars to have the Caspers Ignition tester considering the number of issues that seem to continue creeping up with ignition.

A question are you sure it is boost related and not RPM? Meaning if you were to turn down the boost and ride the RPM's up the scale would you run into the same issue?

No spark I believe would cause for a lean reading but that is only because technically only air would pass through to the o2 sensor. But this would have no effect on your plugs because the heat generated under a lean burn situation would not be generated so your plugs could look wet. Or sooty from a partial burn under a weak spark condition.

 

[Amelio]

hmmmmm all good points, as mentioned race fuel can cause an off white color to the plugs, I did not think of this. A few months ago I had the car at the track and had a few gallons of 110 in the tank, this could explain the lighter color of the plugs. They do not have deposits nor are they crusty they are just more white than tan which leads me to believe it is from the 110oct.

No the car has zero knock, I am sure there is always a possibility of faulty wires but before I went to the track I was having some knock but was able to adjust it out with adding fuel via the TT chip.

As far as RPM or boost issue I am pretty sure it is boost related, i have it turned down now to where it only makes maybe 16-17psi. Since it is turned down it builds boost slower so 1st gear stretches to 15 psi and shift to second and boost will creep up to 16 and the issue occurs. I have had it to where it only made 14psi and there was no issue, this is why I am pretty confident it is boost related.

I have triple check and re adjusted all my intercooler hoses to make sure that is not it. It is a pressure issue but don't know from where or why.....I have not ohmed my coil pack yet but I would think if it was reading higher than normal ohms would the car still run good up to 15psi?

 

[Amelio]

I just tested my coils (type II) all 3 coils were between 5.7 and 5.99 ohms..... Does the caspers ignition tool test the module and the coils? Since my coils ohmed out good the likely hood of them shutting down under load would be low correct? Due to the way it acts all three coils would have to shut down at the same time which does not make sense unless it was the module shutting down correct?

 

[LITLV6]

I'll let you know soon. I am chasin down the EXACT same problem. I thought fuel at first, and now have new Walbro pump, hot wire kit, new injector harness, new siemens 60lb. injectors, replaced both vacuum check valves, MAF, changed to a TT chip (i run partial 110) and i JUST put on a new coil, and control module. OF COURSE, when i went to test it my regulator took a crap and now i'm waiting for a new accufab regulator to show up. I have come to realize that the above comment about weak spark might really be it............ By the way, also have new plugs and Taylor 10mm wires. I should have the part and tested by wednesday afternoon and i'll let ya know :wink:

 

[Amelio]

for a long time I thought I was the only one with strange problems until I got on this board LOL! I also thought that for the past 12 years of playing with these cars I have run across all the weird problems I would ever see and this car never stops to stump me

I have spoke to a few Buick buddies here locally and non of us can seem to put our finger on it. My one buddy said he had a similar issue and it turned out to be his alternator putting out plenty of volts but not enough amps. The more I bang my head against the wall with this issue I really feel it is a spark energy problem but exactly where is the biggest hurdle.

I am interested in hear what you come up with, the only problem being if you did fix the problem what new part was the hero? You have changed a lot and would be hard to determine what exactly was the culprit.

Either way please post your results!

Thanks!

 

[LITLV6]

for a long time I thought I was the only one with strange problems until I got on this board LOL! I also thought that for the past 12 years of playing with these cars I have run across all the weird problems I would ever see and this car never stops to stump me

I have spoke to a few Buick buddies here locally and non of us can seem to put our finger on it. My one buddy said he had a similar issue and it turned out to be his alternator putting out plenty of volts but not enough amps. The more I bang my head against the wall with this issue I really feel it is a spark energy problem but exactly where is the biggest hurdle.

I am interested in hear what you come up with, the only problem being if you did fix the problem what new part was the hero? You have changed a lot and would be hard to determine what exactly was the culprit.

Either way please post your results!

Thanks!

I will post them hopefully tomorrow eve. The only thing i havent tested after the fact is the coil/control module. I DID test it after all of the other changes. So, IF and I mean IF this fixes it then it can ONLY be the coil/control module OR the Fuel Regulator which im hopin comes in the mail today.

I will say that when this problem occured first when i bought the car in march of 07 that i really believe the problem went away after i did the spark plugs and Taylor Performance wires......... That would lead me to believe in the spark problem, maybe the coil was just falling off. I know they normally just work or dont, but 10 years as an electronic specialist will teach you that anything goes with electronics LOL

Oh and i hope more than you that this fixes it lol. I'll let ya know soon enough.

 

[LITLV6]

Ok, so here are the results.......

Lets start by saying i made a haste and assumed diagnosis of my fuel regulator after receiving my new accufab (which is a REALLY nice upgrade) regulator i went to the garage to install it today. Much to my suprise the car still only held 22psi with key on and car wouldnt start. After several moments i finally realized that i made a HUGE oversite. I kinda forgot that my Fuel sending unit isnt quite right so neither is the fuel gauge...... needless to say i realized after bleeding out air from the fuel rail that the car was simply out of gas and I am an idiot! lol lol

Enough babbling about my oversite, my popping problem that only occured from 15psi and up was MOST DEFINATELY the Coil and or Control Module. This was the Gremlin i was chasing for 6 months replacing this and that along the way. I would hope Amelio that your problem is the same as mine, this way you wont have to spend as much as i did chasing the problem lol.

I would like to take a moment to also thank Eric at TurboTweak for the wonderful chip and injectors!! The car runs GREAT!!!! The car is runnin around 25psi in 1st, and 20-21 in 2nd,3rd,and 4th with absolutely ZERO Knock showing up. I cant wait to take it to the track now to see how it does. Amelio good luck i hope your problem is as simple to fix, if i can help at all let me know.......:wink:

 

[Razor]

If the problem happens as the boost increases then you have a bad coil pack.

Bad coil pack will show itself under higher boost and POOOOF like someone cut the spark out..as soon as you lift it starts working normally again.

With these cars you need to have a spare coil pack ignition module, spare MAF, and a spare ecm. If you swap out these parts and still have problems.. your in deep doo doo.

Easy parts to swap out.

 

[LITLV6]

If the problem happens as the boost increases then you have a bad coil pack.

Bad coil pack will show itself under higher boost and POOOOF like someone cut the spark out..as soon as you lift it starts working normally again.

With these cars you need to have a spare coil pack ignition module, spare MAF, and a spare ecm. If you swap out these parts and still have problems.. your in deep doo doo.

Easy parts to swap out.

Nice advise, i wish i would have realized this before now. So my control module could possibly be ok then. maybe i'll test it one day......... 24 year old part though, probably best i replaced it anyway.

 

[Mad_Trbo]

Best advice I can provide is to test the parts! "Buy the CASPER tool" I know at times it seems easier just to swap the part out but truly that at times can turn out to be a waste of money. I can't tell you how many working coil packs and modules I have sitting at the house because the symptom indicated one of those components was the issue.

For example the strangest thing happened, my car always had a hard time starting and I thought it was the calibration on my XFI giving me fits. As I started to push the car into a higher RPM range with additional boost I was losing ignition. I had the casper tester and found the the coil pack to be faulty in the upper rpm range. After beating on the assembly with the tester eventually i got no spark at any rpm. It was an aftermarket module and coil. I figure easy fix go get another one, in the mean time i let a buddy borrow my tester and they did something to it and fried it. This was before I could test the new assembly, I installed the coil and module and the car would not start. I've heard horrow stories about the autozone and advance replacement parts being deffective out the box - probably not really true. So I figured it had to be the part afterall not a week earlier the car ran. So i trade parts again, still no start. So I say bump this and decide back to oem parts. A call to NOs4gn for ACDELCO parts and still no start . After trouble shooting the sensors and determining everything is working. I come to find out the cam sensor either moved or was just on the fringe of working before - explaining the difficult starts. So I re-set the cam sensor and the car now starts amazingly quick indicating where I had it set before was probably just on the fringe.

Point being invest the $123 in the casper tool I think it will save you headache and frustrations in the long run. The ignition system and it's components are fairly simple to trouble shoot with the right tools.

as they say just my .02 cents

 

[Amelio]

Thanks LitlV6 for the update.... I am still digging. Last week I did find my main ground wire from the battery melted from the down pipe with lots of corrosion. After replacing that the loud popping went away and now at 16psi the car just falls on it's face, sounds like all the spark is gone and just lots of pressure escaping back out.

I did test my coils and all three were less than 6 ohms, if the coil pack is going bad I can't see how all three would go at the same time (type II) This leads me to think it is the module failing since that would cause an ignition failure but the only thing that throws me is the car runs great all the time up to 15psi. In my experience a failing module works ok until warm then starts to go down hill real fast. It still could be the module but I am not sure and I don't have the extra cash for the Casper's tool at the moment to verify.

Yesterday I tor into the harness and found one of three ground wires on the back passenger side head broken. One of the grounds is for the fan and the other is to the maf, the one that was broken is ground for a splice for 3 other wires that I did not chase to see what they actually ground. Anyway I repaired it and will put everything back together this weekend and test it out.

If the problem is still there I have a buddy with a GN that I can borrow his coils pack and module. I do have a spare ECM but unfortunately it does not have the larger drivers for my injectors.

I will post the results later, hopefully the broken ground is the culprit.

 

[krazy86t]

I did test my coils and all three were less than 6 ohms, if the coil pack is going bad I can't see how all three would go at the same time (type II) ....It still could be the module but I am not sure and I don't have the extra cash for the Casper's tool at the moment to verify.

you would need to do something funky with sparkplug wires, etc. to use the Caspers tool on a type II ignition. HV connections are totally different alignment. maybe the spark extenders, too?