Pre ignition after installing chip

I had a SCT 4 bank chip installed in 98 GT a few months ago along with a 3:90 gear. Now, when I am driving at 60-70mph and punch it I get horrible detonation. Has anyone had this problem and can offer some advice? It has been doing this ever since the chip was installed.

Now my mechanic thinks it is the fuel pump. At first he thought is could be the Costco gas, 93 octane. I have now gone through about a dozen tanks of Exxon 93 octane with no change. He took out the air silencer in hopes to get more air flowing thinking that would help. Not that I do not trust him because I do. I am just checking to see if he may have not thought of something. The car has 92,000 miles on it.

Any advice would be greatly appreciated.

Thanks,

Bill S

Reply to
Bill S
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Your mechanic thinks it is the fuel pump? He must think you're running lean. Without looking, I'd be inclined to think the chip is running too much advance. Have you talked to the chip vendors?

Dana

Reply to
Dana H. Myers

Was your car dyno'd? Was the A/F mapped? Did you get a flip switch installed with the chip? Sounds like the timing is too far advanced at the higher rpm's, or the A/F is too lean. Quick check #1 - flip the chip to the stock EEC setting (car should run fine no matter the octane) if it doesn't problem is the chip. Quick check #2 - remove the chip and see if you still have the problem (same as #1) Quick check #3 - with the chip in, dump some octane booster into the tank and see if the problem goes away.

If your mechanic can't reprog the chip, that means your car was never mapped and its probably a stock SCT prog which may or may not be right for your particular car.

Normally they're programmed like this:

0 - performance tune, high octane gas, setup for N/A or S/C with all mods accounted for, variations are pretty much endless. (the SCT chip in my '02 is set for 94 octane, 3:73 gears for the speedo recal, advanced timing from 3000 rpm to 6000 rpm, rem'd the rev limiter, traction control set to permanent "off", allowance for exhaust, pulleys) 1 - empty or as in my case, low octane gas, pretty much a stock tune, rem'd the rev limiter, traction cont set to "off". 2 - valet mode, won't rev past 2500rpms for the obvious reason. 3 - empty 4 - Stock EEC program 5, 6 & 7 Car will not run on this setting.

I'd also seriously consider a different mechanic.. you're getting detonation and he wants more air-flow? That'd just lean out the mix assuming that reming the air silencer would increase the airflow drastically enough.. which it won't. He's gonna start throwing parts at a problem because he can't figure it out, when the problem started happening with the chip install.... Personally, I'd look to the chip's tune as being the problem.

3:90 gear. Now, when I am driving at 60-70mph and punch it I get >horrible detonation. Has anyone had this problem and can offer some advice? It has been doing this ever since the chip was installed.

be the Costco gas, 93 octane. I have now gone through about a >dozen tanks of Exxon 93 octane with no change. He took out the air silencer in hopes to get more air flowing thinking that would help. Not >that I do not trust him because I do. I am just checking to see if he may have not thought of something. The car has 92,000 miles on it.

Reply to
Jafo

Bill S wrote: > *I had a SCT 4 bank chip installed in 98 GT a few months ago along with > a 3:90 gear. Now, when I am driving at 60-70mph and punch it I get > horrible detonation. Has anyone had this problem and can offer some > advice? It has been doing this ever since the chip was installed.* > ** > *Now my mechanic thinks it is the fuel pump. At first he thought is > could be the Costco gas, 93 octane. I have now gone through about a > dozen tanks of Exxon 93 octane with no change.

Your mechanic thinks it is the fuel pump? He must think you're running lean. Without looking, I'd be inclined to think the chip is running too much advance. Have you talked to the chip vendors?

Dana

Reply to
Bill S

Jafo,

Thanks for your reply and your advice. I really appreciate such a detailed and complete explanation. This helps me better understand what is going on.

I can get on the car from a dead stop right after the engine warms up and the detonation does not occur. It only occurs when I am already going 40 or higher and get on it.

Answer to your questions: No (but, I live just a few minutes away from Hypertech in Bartlett TN. I hear they do the dyno testing there), do not know, do not know (If he did install a flip switch he did not tell me and I have not noticed anything different while cleaning the interior or engine) By the way, I now have an idea what a flip switch is but do know where it would be installed.

#2 - I can just pull the chip out? I know where it is, passenger side under the dash. #3 - If I put some octane booster in and the problem goes away does that tell me it is the fuel pump, air/fuel mixture or the chip?

He already told me the chip would have to be sent back (again!!) to be re-programmed, the first time was because the speedo was not right (@12 mph to fast). Since I paid for the chip I should be able to deal with JMS directly, shouldn't I? If they programmed the correct gear (3:90) how can it still be off?

The mechanic said he would install a Motorsport 255 pump(?) as the replacement for the stock fuel pump. Is this an unnecessary investment for a car with 92K+?

Was his choice of chip a good one? It sounds like the same chip you have.

Thanks,

Bill S

If your mechanic can't reprog the chip, that means your car was never mapped and its probably a stock SCT prog which may or may not be right for your particular car.

Normally they're programmed like this: 0 - performance tune, high octane gas, setup for N/A or S/C with all mods accounted for, variations are pretty much endless. (the SCT chip in my '02 is set for 94 octane, 3:73 gears for the speedo recal, advanced timing from 3000 rpm to 6000 rpm, rem'd the rev limiter, traction control set to permanent "off", allowance for exhaust, pulleys) 1 - empty or as in my case, low octane gas, pretty much a stock tune, rem'd the rev limiter, traction cont set to "off". 2 - valet mode, won't rev past 2500rpms for the obvious reason. 3 - empty 4 - Stock EEC program 5, 6 & 7 Car will not run on this setting.

I'd also seriously consider a different mechanic.. you're getting detonation and he wants more air-flow? That'd just lean out the mix assuming that reming the air silencer would increase the airflow drastically enough.. which it won't. He's gonna start throwing parts at a problem because he can't figure it out, when the problem started happening with the chip install.... Personally, I'd look to the chip's tune as being the problem.

Reply to
Bill S

IMHO, you're clearly advanced too far. A cooler engine is less likely to detonate, as you warm it up it begins to detonate, especially if you're repeatedly "getting on it" to see if it will detonate.

I'm just guessing, but I really suspect the advance curve in the chip is too aggressive. Fuel pump, maybe, but I would have expected this to cause a lean condition before you changed the chip with associated hot spots and increased detonation. If you changed the chip and suddenly got detonation, my guess is the chip is just tuned too aggressively.

All the technology has really changed, but the basics haven't ;-)

Dana

Reply to
Dana H. Myers

If you go the HyperTech, get one of their chips. Your chip is just plain too aggressive timing wise. If octane booster eliminates or delays the pinging, this proves the.

Check fuel pressure. It should be in the 35 to 40 PSI range through the entire rev range. Change fuel filter and/or install an adjustable FPR to get this pressure. A big pump is not the answer.

bradtx

Reply to
B2723m

Bill, The flip switch is on the end of a cable that attaches to the chip itself, about 30 inches long. Its hard to mount anywhere cuz of its small size, so a lot of installers just route it into the glove box. I'm betting you didn't get one, which means you've probably got the 1100 Blue $265 (single program) and not the 1300 Blue $525 (multiple program).

#2 - Yes you can pull it out, but.. BIG BUT... to avoid damaging the computer or the chip, remove the computer from the panel and unscrew the cover, then pop the chip out. DISCONNECT the battery FIRST!... but you knew that. #3 - Going back to the basics, if the car wasn't detonating prior to the chip, and booster helps, the chip is most likely too aggressive. As Dana and Bradtx said.

Speedo... you didn't happen to have a white face (or other colour) gauge faceplate installed didja? Could just be the needle was put back in the wrong position. On the other hand, it seems that all your problems originate from the chip... bum chip.. bum prog.

FWIW - known problems with chip installs: #1 - probably the most common problem is not adequetly cleaning the contact surfaces on the chip, they should be completely tarnish and coating free. #2 - there's a capacitor or 2 on the chip that can be dislodged if its just jammed into the computer. #3 - messing with the electronics without disconnecting the battery.

I'd try to find someone local that can burn the chip, obviously saves the turnaround time.. SCT may have someone local that is trained and authorized by them to do custom tunes. (Some locales anyways, we've even got one up here in the boonies - that being Toronto area.)

As far as chips go, I replaced my Diablo one with the 1300 Blue and noticed an immediate change in the gitupango factor.. but then the guy here (Steeda.ca) is a qualified tuner and I'd just had the car dyno'd so we knew the A/F was spot on. The Diablo may be a good chip but no one locally could custome tune (burn) it. Diablo dealer just downloads a prog from the internet and burns it on the chip.. much like your case except it only takes a couple of weeks for Diablo to upload the prog.... Bob

Thanks for your reply and your advice. I really appreciate such a detailed and complete explanation. This helps me better understand what is going on.

I can get on the car from a dead stop right after the engine warms up and the detonation does not occur. It only occurs when I am already going 40 or higher and get on it.

Answer to your questions: No (but, I live just a few minutes away from Hypertech in Bartlett TN. I hear they do the dyno testing there), do not know, do not know (If he did install a flip switch he did not tell me and I have not noticed anything different while cleaning the interior or engine) By the way, I now have an idea what a flip switch is but do know where it would be installed.

#2 - I can just pull the chip out? I know where it is, passenger side under the dash. #3 - If I put some octane booster in and the problem goes away does that tell me it is the fuel pump, air/fuel mixture or the chip?

He already told me the chip would have to be sent back (again!!) to be re-programmed, the first time was because the speedo was not right (@12 mph to fast). Since I paid for the chip I should be able to deal with JMS directly, shouldn't I? If they programmed the correct gear (3:90) how can it still be off?

The mechanic said he would install a Motorsport 255 pump(?) as the replacement for the stock fuel pump. Is this an unnecessary investment for a car with 92K+?

Was his choice of chip a good one? It sounds like the same chip you have.

Thanks,

Bill S

If your mechanic can't reprog the chip, that means your car was never mapped and its probably a stock SCT prog which may or may not be right for your particular car.

Normally they're programmed like this: 0 - performance tune, high octane gas, setup for N/A or S/C with all mods accounted for, variations are pretty much endless. (the SCT chip in my '02 is set for 94 octane, 3:73 gears for the speedo recal, advanced timing from 3000 rpm to 6000 rpm, rem'd the rev limiter, traction control set to permanent "off", allowance for exhaust, pulleys) 1 - empty or as in my case, low octane gas, pretty much a stock tune, rem'd the rev limiter, traction cont set to "off". 2 - valet mode, won't rev past 2500rpms for the obvious reason. 3 - empty 4 - Stock EEC program 5, 6 & 7 Car will not run on this setting.

I'd also seriously consider a different mechanic.. you're getting detonation and he wants more air-flow? That'd just lean out the mix assuming that reming the air silencer would increase the airflow drastically enough.. which it won't. He's gonna start throwing parts at a problem because he can't figure it out, when the problem started happening with the chip install.... Personally, I'd look to the chip's tune as being the problem.

Reply to
Jafo

Not all octane boosters are created equal. My experience leaves no doubt at all that the most effective octane boosters are those that contain MMT. The Outlaw Power Shots are my current favorite. If it doesn't say MMT on the label, or list it in the MSDS, it's probably not very effective. You can also detect the presence of MMT by the peculiar odor and pale yellow color of the booster.

As Bradtx says, adding booster may not eliminate pinging, but reduce the tendency to ping. Adding more booster, up to a limit, can have increased effectiveness, but keep in mind that MMT is suspected to taint catalytic converters when used in high concentrations.

Dana

Reply to
Dana H. Myers

Agreed.

I > > If you go the HyperTech, get one of their chips. Your chip is just plain too

Reply to
Jafo

Entering into the unknown, V'ger seeks information used to maintain his Vintage Burgundy 1965 Ford Mustang 2+2 w/289 ci 4v oem A Code V8, C4 Trans,

16x8" Vintage 40 wheels, with BF Goodrich gForce T/A 225/50ZR16 tires, American Racing "Mustang" Centercaps, and a whole lot of other stuff; )
Reply to
V'ger

Sure. I was just commenting on octane boosters in general.

Dana

Reply to
Dana H. Myers

Jafo and All,

You folks are too much. Thanks for all the great responses. I will take a look at the chip tomorrow. My German Shepard tore his dew claw and we just got back from the vet. Dinner is late and the wife is not happy. And if the wife is not happy... you know the rest. I can tell you the chip is all red and he charged me $435 for it. Said it had 4 banks?

Did not know to disconnect the battery. Thanks. Actually, I remember when I noticed the speedo was off. He just pulled back that panel and took the chip out.

I will read this post and the other more in depth tonight or tomorrow morning (before I touch my car) and reply.

Again, thanks so very much everyone!!!

#2 - Yes you can pull it out, but.. BIG BUT... to avoid damaging the computer or the chip, remove the computer from the panel and unscrew the cover, then pop the chip out. DISCONNECT the battery FIRST!... but you knew that. #3 - Going back to the basics, if the car wasn't detonating prior to the chip, and booster helps, the chip is most likely too aggressive. As Dana and Bradtx said.

Speedo... you didn't happen to have a white face (or other colour) gauge faceplate installed didja? Could just be the needle was put back in the wrong position. On the other hand, it seems that all your problems originate from the chip... bum chip.. bum prog.

FWIW - known problems with chip installs: #1 - probably the most common problem is not adequetly cleaning the contact surfaces on the chip, they should be completely tarnish and coating free. #2 - there's a capacitor or 2 on the chip that can be dislodged if its just jammed into the computer. #3 - messing with the electronics without disconnecting the battery.

I'd try to find someone local that can burn the chip, obviously saves the turnaround time.. SCT may have someone local that is trained and authorized by them to do custom tunes. (Some locales anyways, we've even got one up here in the boonies - that being Toronto area.)

As far as chips go, I replaced my Diablo one with the 1300 Blue and noticed an immediate change in the gitupango factor.. but then the guy here (Steeda.ca) is a qualified tuner and I'd just had the car dyno'd so we knew the A/F was spot on. The Diablo may be a good chip but no one locally could custome tune (burn) it. Diablo dealer just downloads a prog from the internet and burns it on the chip.. much like your case except it only takes a couple of weeks for Diablo to upload the prog.... Bob

Thanks for your reply and your advice. I really appreciate such a detailed and complete explanation. This helps me better understand what is going on.

I can get on the car from a dead stop right after the engine warms up and the detonation does not occur. It only occurs when I am already going 40 or higher and get on it.

Answer to your questions: No (but, I live just a few minutes away from Hypertech in Bartlett TN. I hear they do the dyno testing there), do not know, do not know (If he did install a flip switch he did not tell me and I have not noticed anything different while cleaning the interior or engine) By the way, I now have an idea what a flip switch is but do know where it would be installed.

#2 - I can just pull the chip out? I know where it is, passenger side under the dash. #3 - If I put some octane booster in and the problem goes away does that tell me it is the fuel pump, air/fuel mixture or the chip?

He already told me the chip would have to be sent back (again!!) to be re-programmed, the first time was because the speedo was not right (@12 mph to fast). Since I paid for the chip I should be able to deal with JMS directly, shouldn't I? If they programmed the correct gear (3:90) how can it still be off?

The mechanic said he would install a Motorsport 255 pump(?) as the replacement for the stock fuel pump. Is this an unnecessary investment for a car with 92K+?

Was his choice of chip a good one? It sounds like the same chip you have.

Thanks,

Bill S

If your mechanic can't reprog the chip, that means your car was never mapped and its probably a stock SCT prog which may or may not be right for your particular car.

Normally they're programmed like this: 0 - performance tune, high octane gas, setup for N/A or S/C with all mods accounted for, variations are pretty much endless. (the SCT chip in my '02 is set for 94 octane, 3:73 gears for the speedo recal, advanced timing from 3000 rpm to 6000 rpm, rem'd the rev limiter, traction control set to permanent "off", allowance for exhaust, pulleys) 1 - empty or as in my case, low octane gas, pretty much a stock tune, rem'd the rev limiter, traction cont set to "off". 2 - valet mode, won't rev past 2500rpms for the obvious reason. 3 - empty 4 - Stock EEC program 5, 6 & 7 Car will not run on this setting.

I'd also seriously consider a different mechanic.. you're getting detonation and he wants more air-flow? That'd just lean out the mix assuming that reming the air silencer would increase the airflow drastically enough.. which it won't. He's gonna start throwing parts at a problem because he can't figure it out, when the problem started happening with the chip install.... Personally, I'd look to the chip's tune as being the problem.

Reply to
Bill S

gear. Now, when I am driving at 60-70mph and punch it I get horrible detonation. Has anyone had this problem and can offer some advice? It has been doing this ever since the chip was installed.

the Costco gas, 93 octane. I have now gone through about a dozen tanks of Exxon

93 octane with no change. He took out the air silencer in hopes to get more air flowing thinking that would help. Not that I do not trust him because I do. I am just checking to see if he may have not thought of something. The car has 92,000 miles on it.

not sure what the cause is but flowing in more air sure won't fix a detonation problem. Detonation is caused by either not enough fuel (yes it could be your fuel pump) or your ignition is advanced too much. Why don't you have your mechanic check the fuel pressure ? Remove NO-SPAM from email address when replying

Reply to
Rein

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