Detonation

Yeah, maybe you could pull the MAF off and do a visual inspection. make sure the thermistors/thermodes are still bonded to the posts, and that they're clean. Then check all the wiring, starting at the MAF. Look for corroded pins everywhere. Did the motor get washed down at any time here? Simple green is corrosive to aluminum, and if left on the motor too long and if it got inside some connectors and left there, it could hurt your connections. If you were to check the AF numbers, that should tell you pretty quick if the MAF is throwing out some bunk signals.
O2 sensor good? Crosscounts active?
 
The TPS-TEC is a throttle inhancer. It just makes sure the ecm gets the correct voltage at WOT from the TPS. I have unplugged it anyways and still have the problem.
 
My O2s look good and are switching. I had another knew delco one, so I put it in just in case. I haven't washed the engine. I'm running through my head on everything that might have been disturbed when I pulled the intake and heads off. I'm going to really look at the ground wires since they did get pushed aside while doing the work. After I check them out, I'll watch the AF numbers. I'll record the readings when it starts doing it.
 
I would definitely change the spark plug wires. A friend of mine with a TR had a similar problem and he changed the wires and the problem was fixed. :cool: HTH!!!
 
Yeah, I would do an ohm check on all the wires. The plugs that were on my car when I bought it were supposedly new, but an ohm check found 1 wire that had a ton of resistance. The wire core wasnt making contact with the spark plug clip thing.
 
Move the Translator wiring to the MAF away from the dual fan wiring. I had electrical interference with my Trans + after installing my dual fans which created a situation much like you describe. I twisted the Trans + wiring and wrapped it in foil (then grounded the foil to the body). This shielded the Trans + wiring from the fan motors (or fan wiring). Anyway, this fixed my problem.
 
slipstick said:
Move the Translator wiring to the MAF away from the dual fan wiring. I had electrical interference with my Trans + after installing my dual fans which created a situation much like you describe. I twisted the Trans + wiring and wrapped it in foil (then grounded the foil to the body). This shielded the Trans + wiring from the fan motors (or fan wiring). Anyway, this fixed my problem.
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Interesting. I didnt like the places most people mount the translator, cause it looks sloppy. I mounted mine literally maybe 2 inches from the fan motor, ontop of the intercooler, right in the center. The whole setup looks clean and there isnt a big cluster of wires to hide. Now that i think about your post, I wonder if Im creating any issues by having it there. The car runs ok with the exception of a rough idle after the car has been driven awhile, been shut off and restarted. But it's always had that problem, and isnt nearly as bad as it used to be. Crap I dont want to move that translator again.
 
Well, I checked all the ground wires and they looked fine. I tood the MAF off and it looked fine. My laptop battery was dead, so I used another scanner to try and record data when it would do what its doing. Anyways, from what I could record, MAF was at 255, TPS 4.5volts or higher, 02s were around high 700s to low 800s. I also found another crank sensor I didn't know I had saved and put it on. I think what I'm going to do is get some more plug wires and in between, see if I can find someone with a MAF I can hook up and try. It really feels like ignition breaking down to me.
 
I hope you have better luck than me, but your car sounds just like mine after a cam lobe was wiped out. Pull each plug wire at the spark plug one at a time while the engine is at idle. The engine should run rough once each one is removed. If the engine does not change it's idle, that is the cylinder that is giving you the problem. You can at least narrow it down to which cylinder is causing the problem and work from there.

Do a search on wiping out the cam lobe. One cylinder in particular seems to be the problem one - I just can't remember which one. I know it was on the driver side though, maybe the closest to the front of the car. It took my Buick guru quite some time to figure it out. About three weeks later the same thing happened to his car.
 
tmsbuic said:
Well, I checked all the ground wires and they looked fine. I tood the MAF off and it looked fine. My laptop battery was dead, so I used another scanner to try and record data when it would do what its doing. Anyways, from what I could record, MAF was at 255, TPS 4.5volts or higher, 02s were around high 700s to low 800s. I also found another crank sensor I didn't know I had saved and put it on. I think what I'm going to do is get some more plug wires and in between, see if I can find someone with a MAF I can hook up and try. It really feels like ignition breaking down to me.
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This post is as much about troubleshooting technique as it is the actual issue at hand.

I'm not an expert, but here's my usual train of thought. I like to begin a troubleshooting session with the assumption that a) there is only one thing wrong, not two or three simultaneous problems 2) everything that was basically untouched and working prior to the rebuild is working after the rebuild 3) that whatever is wrong, is directly related to the specific changes made during the rebuild (which shows the wisdom of making only 1 change at a time) and 4) if none of the above, the problem is not related to what was changed but instead a consequence of the rebuild process.

Well that narrows it down! :D

I'd like to think that nothing happened to your crank sensor, fuel pump, fuel pressure, fuel injectors, or even your plug wires for that matter. The reason I sometimes check these items is the thought that they may have been marginal before, and now with the increased pressure in the cylinders they have crossed the threshold. Some of these parts are easy to swap and quickly rule out. Sometimes, its a waste of time.

Does anyone have any thoughts on another way to approach this? Bruce? Steve?

We've all troubleshot a hundred times and the answers just seem to elude you..till..you find it! :tongue:

I'm still thinking the tune is not perfect. What is the chip timing set at?
 
The chip is a TT street chip for 93 w/alky(I've mailed Eric some cores and I'm getting him to make a fresh chip for my setup anyways). I think the timing is 23/20 on this chip now. On the data I was able to record during the problem, the timing was at 19. What really makes me feel that it has to be something simple is the car runs fine up until 5 or more lbs of boost. You will start feeling it cutting out some and as the boost goes a little higher toward 10 to 15 lbs, it backfires pretty bad. I have made sure my boost control won't take me past 15 for testing this. I can't really go WOT very long because the car will jump up in boost quick and backfire. If I slowly roll into the throttle while cruising and the boost starts climbing past 5psi, then you can feel it starting to cut out. It does not show any Knock retard while it is cutting out on the scanner. I have my alky coming on around 5 psi, but I can turn it off without any change. Heck, the engine should run fine at 5 psi even on 87 octane fuel since I don't have any radical compression going on. It just seems it has to be ignition, because I'm not getting any knock retard or knock counts.
 
Have you changed out your module? Sounds just like a problem we had and we had changed the module but the new one was no good. Hope this helps. Hi Tech6
 
sounds like a module possibly, but thats an expensive "possibly". Get with somebody local and swap some parts out. Also have you checked to see if the turbo may be blowing oil at all? Not sure if it would cause a pop or backfire but it would cause detonation at even light boost. Also I wanted to let you know that the BLMs at 110 is telling you something, on Erics chips im almost positive this is bottomed out, and it is sensing a rich condition and trying to lean it out which may be counterproductive to what you are trying to do. I may be repeating as i didn't read every post in the thread, but are you sure you have a good ground on the back of both the heads (the one on the firewall... and the cluster on the passengerside from the harness?) Other than that i would wait for a new chip, as you are flowing a whole lot more air at the same throttle. I wasn't sure if you already had a chip for this combo? or if you had and now its being tweaked a bit. If its the old chip used with the stock intercooler, heads and DP then a new chip may cure it. Good luck
 
This sounds like a lobe going flat. Except, you've got a roller cam, and, they're tough! So, I'll go with the module, as JDSfastGN mentioned.
The modules can cause all kinds of weirdness. Swap it out with a known good one. Let us know!
 
VadersV6 said:
..................What gas are you running? Arco or BP? That gas is like liquid dynamite. Really prone to Detonation. Chevron, 76, Mobil gas- I can run 89 octane with alky, 27/25 timing, 23 lbs of boost. Arco (same as BP), I can only run 20 lbs with 91 octane with alky, and have to pull 2 degrees of timing. people say its no different than other gas. That is total BS. Every person I know who uses this gas ends up with major pinging issues. These numbers of mine are not just an opinion but real data. When I tell people about my numbers with my scan tool and tuning stuff, they are much more convinced that there is something to this cheap gas theory.
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Brent:
I know that you have much more experience than I do in this area, but I will post my findings anyway. I have my boost solenoid currently disconnected and the vacuun line plugged due to what I suspect is a gone bad boost solenoid. I regurally run Arco in both my vette and the turbo Buick. I have felt that in the last 15 years or so, Arco is about as good as anything else.
With Arco 91 from a freeway stomp from about 65, the sm will register about 3.8 to 4.0 knock retard, at about a bar or so below the red/orange zone. I filled the tank this afternoon with Chevron 91, did the usual freeway stomp from 65 or so, and had exactly the same results, (sm readings) 3.9 to 4.0, 3 out of 3 runs. I don't doubt your readings, but I feel that in the method that you compared your scenario, it was not exactly apples to apples. If you are in the position to make identical runs with identical settings, only switching the 2 brands of gas, I would like to hear the results. Please keep me posted, you might be onto something, but you need to do more of a side by side comparasion. happy holidays, dude, you and your family both/all
 
Im surprised your GN runs ok with Arco. Just about every person Ive ever known who ran that stuff complained about their car suddenly pinging and running terrible. Its even the case in my wifes 2001 V6 mustang. She thows arco in it, and after it warms up, its got a bunch of tip in pinging. Every car Ive had ran like crap on it as well. I remember back in the day, the hot ticket for hot rods was Shell premium 92. It had this red dye in it that made it look different than all the other gas. For some reason everyone thought the red dye meant it was better, and that this 92 octane was better than the other 92 octane without the dye, lol. A guy I used to work with's wife works for a oil refinery that makes arco gas, and she says its all the same. But shes not a chemist. She's a PR agent. The lowered cost of the arco gas has to come from cutting a corner somewhere. Maybe they arent as strict when it comes to keeping water out of the big tanks or keeping them clean/maintaining the pumps and filters...maybe they skip 1 of the refining processes. Who knows. Ive actually been running arco now and then cause its on the way to work. But ever since I saw the added KR under boost, I decided to never floor it while its in the tank. Another thing to consider is that winter and summer gas are different formulas. My cars always ran worse on winter gas, which sucks cause thats when the cold weather is there.
 
Brent: After re-reading your post, it does seem that your comparasion was pretty much side by side, about as much as can be.
Makes me wonder about station to station variation.
 
My money on the cam sensor, either 180 out, not set correctly, or the window wheel has come loose and has been retightned without re-setting the wheel (the very small metal tab can and does shear very easily) and will result in some ear splitting back fires.

Other than that my second thought goes to being cross wired.

Good luck,
 
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