Please help. I am losing the battle

[blackbuick87]

I have been battling this problem for a month now, and I am not getting anywhere. The car just keep popping and missing when I get into the boost. I was thinking too much FP since whenever it pops I am always higher than 850 on the O2's, sometimes as high as 900. but turning down the FP has changed nothing. I cannot get past half throttle, ever. I also have leaded 110 in the tank now, which has not helped.

I have changed in the last month:
Coil pack
plugs
wires
changed MAF over to LT1 w/translator
added an adjustable FPR
hot wire kit
All changed one at a time, with mixed results. I have also:
tried different FP's from 39psi line off to 49 psi line off.
I have tried unplugging my O2 sensor, no change
tried a RA 93 and Thrasher 108

The only things I can think to try are another module or maybe the cam sensor is out of adjustment?!?!?

I am desperate. please please give me some ideas I have not thought of. The car idles perfect now and has no hesitation. It just pops between 6 and 12 lbs

 

[1970gsx]

Have you noticed any lights flickering when it pops? Like the headlights and SES light? If so, it's probably the pass. side header hitting the + cable to the starter.

 

[Turbo__Tim]

Damm Bob, usally when things get this far it's because you have exchanged a bad part for a bad part. Assuming you bought good quality spark plug wires, then you are looking at the coil pack, module. or the ecm.

Even though you have good mid-range power, I would still do a compression check. First. Then seek out people that have known good ignition parts to swap in.

What is the history of the car. How long have you had it. When did the problem start?

Maybe finding a good shop with an oscilloscope will elliminate, of find the source of the problem.

You have a tough one there, that's for sure. 99% of the time the problem would have been corrected with what you hqve done...

Good luck guy...

 

[blackbuick87]

I dont think I have a compression problem. It starts immediately and the only oil I use is coming out the rear main seal

I have no SES lights.

What are the symptoms of a bad module?

The car has a Jaspers block with about 15000 miles on it, based on what the previous owner told me. Car has 76K. I have the original block in my Garage. When I bought the car I got a box of parts:
Screwed up turbo, coil pack, and two modules. The previous owner did not know if they worked and I dont either. I dont know how to test them however. All replacement parts were from Ramchargers.

 

[Turbo__Tim]

Hmmm, disconnect the knock sensor, and try a quick run. It's located drivers side of the motor, back at the firewall.

 

[TurboT2496]

Try a new O2 sensor

I don't think unplugging the current o2 sensor and running the car without it eliminates the sensor as the culprit. Try a new delco sensor and see if that fixes it. I've seen several sensors that were bad and never set a code. You say the car is running rich and thats a definite symptom of a bad o2 sensor. When the sensor gets old and develops deposits on it, it doesn't read as well and will screw up the fuel mixture. Are you getting any Knock Retard when this popping happens?? If not, it shouldn't be a problem with the knock sensor. Also take Tims advice and find someone with a good running car you can borrow parts off of and stop throwing money at this problem. That can be verrry frustrating especially if you replace an old good part with a new bad one. Been there, done that ---- not fun. Good Luck.

 

[NastyGn]

My bet would be the coil pak. If you don't know some one with a tester then find someone with a good running car and see if the problem stops.

There is also a test for the coil pak but will not always tell you for sure, take a test meter and check the ohms of each coil (from post to post on the same coil) this should be around 12.

Good Luck, I hate electrical problems

 

[blackbuick87]

I am not getting KR when the problem happens. I do have another O2 sensor and will try that.

As far as the coil pack goes, I replaced the old one and it read around 12.5 on all the posts. The new one I replaced at with every post read high 10's (mostly 10.90's)
Is that significant?

 

[Hawaiian Turbo]

Did you check 1970gsx"s post?? That happened to me once, only when the motor torqued, the wires were shorting out,other that it ran just fine. HTH

 

[Eric Stage I]

I agree with Neal, sounds like a spark problem. What spark plug gap do you run? Try reducing the gap to .025" to see if it helps.

Eric

 

[blackbuick87]

I am going to bring the car into work and jack it up and get under it and see if I can find anywhere that it is grounding out. I have tried changing the gap to .032 with no help. I have an O2 sensor at home and will try that also.

The voltage stays at 13.5 when it acts up, does not fluctuate. Unfortunately I dont know anyone with a TR around here to try swapping ECM's.

What are the symptoms of a bad module and is there any way to test them

 

[6=8]

Try some CD2

I have been living with the same problem for about a year. I know that sticky valves can cause the symtoms you describe, but with only 15,000 possible miles on your engine, I'm not so sure.

I looked through your symptoms and they exactly match with my sticky valve issue (Including your o2 readings) I was/am having. I'm in line to replace the stock valve springs on my 150,000 mi daily driver.

Try running a bottle of CD2 (or other oil additive) in the oil to see if you notice any improvements. (If you don't, just change the oil later.) I did this and it was like night and day! It started to clear the problem up in about 2 days of driving, allowing me to move past 1/2 throttle and into the 13 PSI range (Never quite full throttle) for a while, then it came back about 1 month later. If your valves don't completely close, you can imagine what happens when you start to add a little boost!

Your problem may even include a broken spring or 2, given the low miles on your setup and the fact that it seemed to suddenly happen. Is it possible that the valve springs installed were incorrect for the application? Since you have almost exhausted all electrical possibilities, it may be time to look a little closer at the mechanical ones.

Hope this helps. Good Luck!

 

[blackbuick87]

6=8, you have given me another possibilty. I dont think there is a stuck valve but the cracked valve spring could produce the symptoms I have . I hope its not but if the o2 sensor is not the culprit, and its not the module, you never know.

The engine was assembled by Jaspers so I have to hope they knew what they were doing when they put it together and used the right components.

 

[6=8]

Hello blackbuick87,
I didn't know if you had Jaspers do the long or short block thing. Since they put it all together, you are right... the springs are probably correct! But like you say, you never know. Could still be a defective spring...

The items you have listed were too damn close to my problem. I just had to throw that idea out there!

I really hope it is the o2 sensor. That's an easy fix!

Later!

 

[blackbuick87]

Well I am praying now. I just changed the O2 and went out and beat the piss out of my car, drove about 10 miles and boosted it to 20psi many times. Man I hate testing these things
And it ran good. I still have 110 leaded in there so I am going to go ahead and order another sensor, but hopefully I have found the problem!!!!

 

[blackbuick87]

Oh, BTW, thanks to everyone that took the time to help. Without this board I would be screwed

 

[TurboT2496]

Good Job

Glad to hear ya solved the problem. Now go pound some mustangs.