Car Wars: Detonation Strikes Back

95mustanggt · 08-22-2001, 02:20 PM

This one is for the experienced guys out there or those who have solved detonation problems on the 94/95 GT's:

Well, I have a little bit of time so I am going to post my story and hopefully someone can give me a few ideas so I can fix the car quickly. I can't stand to lose to another dam Mazada or something else!

I have been having bad detonation since I drove down from Canada.

If the A/C is on the car detonates like no tomorrow. If you turn the A/C off after it's been on the car still detonates.

If you do not turn the A/C on or leave it off and shut the car down for awhile it runs with no detonation, for the most part.

When the car is cool it seems to run pretty good. Once the car gets a little warm it will do 1 of 2 things:

1. Run like crap with no power but no detonation (that how you lose or tie races with mazda's

)

2. Runs really strong, but there is a hint of detonation between 3500-4500 RPM. (that's how you take chicks driving LT1's

)

The problem is I never know how the car is going to run!

Here is what I have done to date:

I have replaced the Intake Air Temp Sensor and the TPS sensor (it was over 1.0 V). There are no KOEO codes, and the only KOER code was a 123 which was the TPS.

The Continuous memory test is giving a code however and I can't interpret it. I have said this before but It goes like this:

After 2 rounds of 111 111's it pauses 6 seconds, flash, pause 5 seconds, flash, pause 2 seconds, 1 flash, pause 2 seconds, 2 flashes, pause 2 seconds, 3 flashes.

I have not checked any more sensors, but will be working this weekend on it. I am just looking for someone to maybe give me an idea or 2 on something to try so I don't have to walk through the whole dam electrical system.

I was going to start with the EGR, then the MAF, then the Oxygen sensors, Then recheck all the vacuum lines (so far I've only half-a$$ed checked all the vacuum lines)

I've also pulled the Superchips chip.

Any Ideas???

------------------
1995 Mustang GT

[This message has been edited by 95mustanggt (edited 08-22-2001).]

jimberg · 08-22-2001, 02:54 PM

Have you reset the computer since you changed the TPS? If you haven't, that would explain why the continuous code is still there. It's also a good idea to reset the computer after changing a major sensor like O2 sensors and TPS.

What voltages are you getting from the TPS now?

Have you done a Key On Engine Running test and what were the results?

What is the timing set at and did you check it with the SPOUT jumper removed?

How hot would you say your car gets when this starts to happen?

Do you have a friend that you can exchange MAF sensors with when it starts to act up?

------------------
351W 89 Mustang GT Convertible

95mustanggt · 08-22-2001, 03:47 PM

Quote:

Originally posted by jimberg:
Have you reset the computer since you changed the TPS? If you haven't, that would explain why the continuous code is still there. It's also a good idea to reset the computer after changing a major sensor like O2 sensors and TPS.

What voltages are you getting from the TPS now?

Have you done a Key On Engine Running test and what were the results?

What is the timing set at and did you check it with the SPOUT jumper removed?

How hot would you say your car gets when this starts to happen?

Do you have a friend that you can exchange MAF sensors with when it starts to act up?

I did reset the computer after the sensor change. Although I have not yet checked the voltage on it now. I was going to do that this weekend.

The KOEO Test has been doing the same thing. I have not done the KOER test since the TPS change.

Timing is at 10*, changed with the SPOUT removed. The timing with the SPOUT in, I never did check that after I changed the timing to 10*. But when the timing was set mechanically at 0*, with the SPOUT connected the Timing was a little over 10* (11 maybe 12)

Heat, well I have to go by the dumby gauge in the car, but once it reaches the "N" in "normal" things get funny. If the A/C is turned on the temp will shoot up past the "M". I assumed that this was from the detonation.

Unfortunately the only guy I know here in Dallas, is Hammer and he has a 98 (not stock) and an 83 (not an MAF car).

I'm also running Mobil 93 Octane fuel.

Do you think if the EGR was plugging that the combustion temperatures could get hot enough to start the detonation? That was one of my theories, what do you think?

------------------
1995 Mustang GT

jimberg · 08-22-2001, 04:30 PM

You know what, I think I was chatting with Hammer about this the other night. He mentioned a friend with pinging problems. Could that be you?

He said you were getting a code related to the TPS and the IAT. Is he in the process of giving you a hand?

The IAT (Intake Air Temperature, also known as Air Charge Temperature (ACT) ) tells the computer what temperature the air is. The higher the temp, the lower the voltage the ACT will return. From what Hammer said, you're getting a code 112 which says that your ACT is below minimum voltage. This means that the computer thinks the air coming in is above 248 degrees. It will compensate by removing fuel since hot air means less oxygen. Going lean like that is what is causing your pinging and excessive heat.

If I'm wrong about you being the friend that Hammer was talking about, sorry, and we'll keep looking. If you are, though, check the ACT (IAT) circuitry. The easiest thing to do would be to just replace it the ACT. They're about $30 I think.

Good luck.

------------------
351W 89 Mustang GT Convertible

[This message has been edited by jimberg (edited 08-22-2001).]

[This message has been edited by jimberg (edited 08-22-2001).]

andy669 · 08-22-2001, 08:49 PM

I see youve already replaced the ACT and it made no difference. I would check the connections on the plug. Have you gotten rid of your stock air box and the mass air meter plastic housing? The ACT harness plugs right into the MAF harness. The ACT is supposed to pull timing. It sounds possibly like it isnt. The next time it acts up, unplug the sum-***** and see if it makes a difference.
andy

------------------
3 Black 94 GT Vert. AODE/TKO conversion, 3:73's, ported X-305's, GT40 manifolds, 75mm TB, 30lbers, PMS, 300 horse Top Gun wet kit, and all the other little stuff

95mustanggt · 08-22-2001, 10:43 PM

Did some testing:

Tested the IAT, Resistance was 20K ohms + (brand new IAT, or ACT)
The TPS was between .98 and 1.04 (Brand new TPS)
The voltage on the MAF was 8.04 V, battery voltage was 14.08

Mechanical timing (no SPOUT) was dead on 10*. With SPOUT connected, timing was between 30 and 40*. I was hard to read and was jumping around some.

After pulling the MAF and the IAT connections I ran the KOEO and KOER tests.

The KOEO test had codes, 113, 157 and 158. The 113 is the IAT the 157 and 158 are the MAF codes, but one is voltage too high one is voltage too low. I would expect a code because I took the connector off, but both high and low?? What do you think?

I cleared the codes (pulled the jumper wire mid test) and made sure there was no codes. I then took it for a ride. Ran great

.

I then stopped at 7-11 and when I started it up again the idle was funny, (unstable and rough, maybe a little on the low side)

Soon as I got on it, detonation. But only once or twice. Then it was running pretty good every now and then. But I checked codes again it was still clean.

Thanks for the help jim.

Any Ideas

moosejaw · 08-23-2001, 01:37 AM

Well you could check all the engine and chassis grounds. The computer hates bad grounds. It won't get enough voltage (or to large a voltage drop) and therefore attached sensors will not funtion properly. This includes fuel injectors. This could cause it to lean out and cause the high temp, detonation and lack of power. Sounds crazy? I had it happen to me. The engine to chassis ground was bad and the car was ok for about 30 min of driving. Then things would get bad. Detonation, high temps.... it sucked.

This is just another idea that seems to fit your symptoms. Hey, if you feel like just add a couple more ground lines to the block, chassis, alternator and battery. The more the merry.

------------------
Live near St.Louis?
Check out Mustang Muscle and Dyno in High Ridge, MO
Check out my ride.

95mustanggt · 08-23-2001, 08:50 AM

I have checked the ground on the block to the frame and to the battery. It is all good.

However now that you mention it, when I am testing voltage on a sensor I have trouble getting a reading using the ground on the harness, so I've been using the chasis for ground....

I noticed that the voltage on my TPS was still over 1.0V? The sensor is brand new, and there is no longer any codes on it, could it be caused by something else?

If the MAF was bad, could it cause the TPS voltage to go up? When I changed the Intake Air temp sensor, one side was totally covered by dirt, after last nights chat, I though perhaps my MAF is too dirty.

jimberg · 08-23-2001, 10:00 AM

Adjust the TPS voltage by loosening the two screws while the ignition is in the on position and then rotate it until it reads about .97 volts.

Check the ground of the ECM itself.

------------------
351W 89 Mustang GT Convertible

95mustanggt · 08-23-2001, 10:35 AM

Quote:

Originally posted by jimberg:
Adjust the TPS voltage by loosening the two screws while the ignition is in the on position and then rotate it until it reads about .97 volts.

Check the ground of the ECM itself.

Got ya, I just replaced the TPS so I find it funny that the voltage is too high again. I'll try to adjust it.

The ground on the ECM, I didn't think about that. I'll check it.

thanks jim

moponys · 08-23-2001, 10:54 AM

The Superchip that you removed; was it a generic one or a custom chip burned specifically for your car? I'm having similar problems and am waiting for custom burned JMS chip for my stang.

------------------
TFS twisted wedge heads, TFS street intake, Lunati cam .500/.510 218/226, BBK FPR
BBK shorties, BBK 70mm tb, Pro-m 75mm, ASP pulleys, FMS 3:73, Transgo shiftkit
Flowmasters, Bassani x-pipe, K&N FIPK, FMS 1.6 roller rockers, 9mm wires,24lbs injectors,
190lph fuel pump, MSD cap and rotor, 18" wheels w/street tires

95mustanggt · 08-23-2001, 02:20 PM

Quote:

Originally posted by moponys:
The Superchip that you removed; was it a generic one or a custom chip burned specifically for your car? I'm having similar problems and am waiting for custom burned JMS chip for my stang.

Not sure you'd have to ask fastang

andy669 · 08-23-2001, 02:36 PM

the 94/95 tps has steel inserts where the bolts go through. you dont get much adjustment out of them when turning, sure makes it tough!
andy

------------------
3 Black 94 GT Vert. AODE/TKO conversion, 3:73's, ported X-305's, GT40 manifolds, 75mm TB, 30lbers, PMS, 300 horse Top Gun wet kit, and all the other little stuff

moponys · 08-23-2001, 03:00 PM

Isn't that you 95mustanggt that said "I've also pulled the superchips chip". I don't get the part about fastang...

------------------
TFS twisted wedge heads, TFS street intake, Lunati cam .500/.510 218/226, BBK FPR
BBK shorties, BBK 70mm tb, Pro-m 75mm, ASP pulleys, FMS 3:73, Transgo shiftkit
Flowmasters, Bassani x-pipe, K&N FIPK, FMS 1.6 roller rockers, 9mm wires,24lbs injectors,
190lph fuel pump, MSD cap and rotor, 18" wheels w/street tires

95mustanggt · 08-24-2001, 08:44 AM

Quote:

Originally posted by moponys:
Isn't that you 95mustanggt that said "I've also pulled the superchips chip". I don't get the part about fastang...

I pulled the chip, but I didn't buy it new. fastang sent it to me. So he would know more about it than I.

fastang is one good guy.

moponys · 08-24-2001, 12:58 PM

ooohh gotcha...

------------------
TFS twisted wedge heads, TFS street intake, Lunati cam .500/.510 218/226, BBK FPR
BBK shorties, BBK 70mm tb, Pro-m 75mm, ASP pulleys, FMS 3:73, Transgo shiftkit
Flowmasters, Bassani x-pipe, K&N FIPK, FMS 1.6 roller rockers, 9mm wires,24lbs injectors,
190lph fuel pump, MSD cap and rotor, 18" wheels w/street tires

08-22-2001, 02:20 PM	#1
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Car Wars: Detonation Strikes Back This one is for the experienced guys out there or those who have solved detonation problems on the 94/95 GT's: Well, I have a little bit of time so I am going to post my story and hopefully someone can give me a few ideas so I can fix the car quickly. I can't stand to lose to another dam Mazada or something else! I have been having bad detonation since I drove down from Canada. If the A/C is on the car detonates like no tomorrow. If you turn the A/C off after it's been on the car still detonates. If you do not turn the A/C on or leave it off and shut the car down for awhile it runs with no detonation, for the most part. When the car is cool it seems to run pretty good. Once the car gets a little warm it will do 1 of 2 things: 1. Run like crap with no power but no detonation (that how you lose or tie races with mazda's ) 2. Runs really strong, but there is a hint of detonation between 3500-4500 RPM. (that's how you take chicks driving LT1's ) The problem is I never know how the car is going to run! Here is what I have done to date: I have replaced the Intake Air Temp Sensor and the TPS sensor (it was over 1.0 V). There are no KOEO codes, and the only KOER code was a 123 which was the TPS. The Continuous memory test is giving a code however and I can't interpret it. I have said this before but It goes like this: After 2 rounds of 111 111's it pauses 6 seconds, flash, pause 5 seconds, flash, pause 2 seconds, 1 flash, pause 2 seconds, 2 flashes, pause 2 seconds, 3 flashes. I have not checked any more sensors, but will be working this weekend on it. I am just looking for someone to maybe give me an idea or 2 on something to try so I don't have to walk through the whole dam electrical system. I was going to start with the EGR, then the MAF, then the Oxygen sensors, Then recheck all the vacuum lines (so far I've only half-a$$ed checked all the vacuum lines) I've also pulled the Superchips chip. Any Ideas??? ------------------ 1995 Mustang GT [This message has been edited by 95mustanggt (edited 08-22-2001).]

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
I'm back.....And still Crazy.	Mercury	Blue Oval Lounge	14	10-30-2002 02:41 AM
I'm back, anyone miss me?	rustang girl	Blue Oval Lounge	18	10-10-2002 11:34 PM
Back in the Game......	1969Mach1	Blue Oval Lounge	27	10-08-2002 10:56 PM
Back from the Track - Good News/Bad News with Diablo	apenn	Modular Madness	1	09-22-2002 02:50 AM
Time to go back to school.	Unit 5302	Modular Madness	12	04-27-2002 03:46 PM

08-22-2001, 02:54 PM	#2
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	Have you reset the computer since you changed the TPS? If you haven't, that would explain why the continuous code is still there. It's also a good idea to reset the computer after changing a major sensor like O2 sensors and TPS. What voltages are you getting from the TPS now? Have you done a Key On Engine Running test and what were the results? What is the timing set at and did you check it with the SPOUT jumper removed? How hot would you say your car gets when this starts to happen? Do you have a friend that you can exchange MAF sensors with when it starts to act up? ------------------ 351W 89 Mustang GT Convertible

08-22-2001, 04:30 PM	#4
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	You know what, I think I was chatting with Hammer about this the other night. He mentioned a friend with pinging problems. Could that be you? He said you were getting a code related to the TPS and the IAT. Is he in the process of giving you a hand? The IAT (Intake Air Temperature, also known as Air Charge Temperature (ACT) ) tells the computer what temperature the air is. The higher the temp, the lower the voltage the ACT will return. From what Hammer said, you're getting a code 112 which says that your ACT is below minimum voltage. This means that the computer thinks the air coming in is above 248 degrees. It will compensate by removing fuel since hot air means less oxygen. Going lean like that is what is causing your pinging and excessive heat. If I'm wrong about you being the friend that Hammer was talking about, sorry, and we'll keep looking. If you are, though, check the ACT (IAT) circuitry. The easiest thing to do would be to just replace it the ACT. They're about $30 I think. Good luck. ------------------ 351W 89 Mustang GT Convertible [This message has been edited by jimberg (edited 08-22-2001).] [This message has been edited by jimberg (edited 08-22-2001).]

08-22-2001, 08:49 PM	#5
andy669 Registered Member Join Date: Jan 2001 Location: Moline Il Posts: 901	I see youve already replaced the ACT and it made no difference. I would check the connections on the plug. Have you gotten rid of your stock air box and the mass air meter plastic housing? The ACT harness plugs right into the MAF harness. The ACT is supposed to pull timing. It sounds possibly like it isnt. The next time it acts up, unplug the sum-***** and see if it makes a difference. andy ------------------ 3 Black 94 GT Vert. AODE/TKO conversion, 3:73's, ported X-305's, GT40 manifolds, 75mm TB, 30lbers, PMS, 300 horse Top Gun wet kit, and all the other little stuff

08-22-2001, 10:43 PM	#6
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Did some testing: Tested the IAT, Resistance was 20K ohms + (brand new IAT, or ACT) The TPS was between .98 and 1.04 (Brand new TPS) The voltage on the MAF was 8.04 V, battery voltage was 14.08 Mechanical timing (no SPOUT) was dead on 10. With SPOUT connected, timing was between 30 and 40. I was hard to read and was jumping around some. After pulling the MAF and the IAT connections I ran the KOEO and KOER tests. The KOEO test had codes, 113, 157 and 158. The 113 is the IAT the 157 and 158 are the MAF codes, but one is voltage too high one is voltage too low. I would expect a code because I took the connector off, but both high and low?? What do you think? I cleared the codes (pulled the jumper wire mid test) and made sure there was no codes. I then took it for a ride. Ran great . I then stopped at 7-11 and when I started it up again the idle was funny, (unstable and rough, maybe a little on the low side) Soon as I got on it, detonation. But only once or twice. Then it was running pretty good every now and then. But I checked codes again it was still clean. Thanks for the help jim. Any Ideas

08-23-2001, 01:37 AM	#7
moosejaw Registered Member Join Date: Apr 1999 Location: St.Louis,MO Posts: 274	Well you could check all the engine and chassis grounds. The computer hates bad grounds. It won't get enough voltage (or to large a voltage drop) and therefore attached sensors will not funtion properly. This includes fuel injectors. This could cause it to lean out and cause the high temp, detonation and lack of power. Sounds crazy? I had it happen to me. The engine to chassis ground was bad and the car was ok for about 30 min of driving. Then things would get bad. Detonation, high temps.... it sucked. This is just another idea that seems to fit your symptoms. Hey, if you feel like just add a couple more ground lines to the block, chassis, alternator and battery. The more the merry. ------------------ Live near St.Louis? Check out Mustang Muscle and Dyno in High Ridge, MO Check out my ride.

08-23-2001, 08:50 AM	#8
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	I have checked the ground on the block to the frame and to the battery. It is all good. However now that you mention it, when I am testing voltage on a sensor I have trouble getting a reading using the ground on the harness, so I've been using the chasis for ground.... I noticed that the voltage on my TPS was still over 1.0V? The sensor is brand new, and there is no longer any codes on it, could it be caused by something else? If the MAF was bad, could it cause the TPS voltage to go up? When I changed the Intake Air temp sensor, one side was totally covered by dirt, after last nights chat, I though perhaps my MAF is too dirty.

08-23-2001, 10:00 AM	#9
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	Adjust the TPS voltage by loosening the two screws while the ignition is in the on position and then rotate it until it reads about .97 volts. Check the ground of the ECM itself. ------------------ 351W 89 Mustang GT Convertible

08-23-2001, 10:54 AM	#11
moponys Registered Member Join Date: May 2001 Location: Antioch, CA 94521 Posts: 181	The Superchip that you removed; was it a generic one or a custom chip burned specifically for your car? I'm having similar problems and am waiting for custom burned JMS chip for my stang. ------------------ TFS twisted wedge heads, TFS street intake, Lunati cam .500/.510 218/226, BBK FPR BBK shorties, BBK 70mm tb, Pro-m 75mm, ASP pulleys, FMS 3:73, Transgo shiftkit Flowmasters, Bassani x-pipe, K&N FIPK, FMS 1.6 roller rockers, 9mm wires,24lbs injectors, 190lph fuel pump, MSD cap and rotor, 18" wheels w/street tires

08-23-2001, 02:36 PM	#13
andy669 Registered Member Join Date: Jan 2001 Location: Moline Il Posts: 901	the 94/95 tps has steel inserts where the bolts go through. you dont get much adjustment out of them when turning, sure makes it tough! andy ------------------ 3 Black 94 GT Vert. AODE/TKO conversion, 3:73's, ported X-305's, GT40 manifolds, 75mm TB, 30lbers, PMS, 300 horse Top Gun wet kit, and all the other little stuff

08-23-2001, 03:00 PM	#14
moponys Registered Member Join Date: May 2001 Location: Antioch, CA 94521 Posts: 181	Isn't that you 95mustanggt that said "I've also pulled the superchips chip". I don't get the part about fastang... ------------------ TFS twisted wedge heads, TFS street intake, Lunati cam .500/.510 218/226, BBK FPR BBK shorties, BBK 70mm tb, Pro-m 75mm, ASP pulleys, FMS 3:73, Transgo shiftkit Flowmasters, Bassani x-pipe, K&N FIPK, FMS 1.6 roller rockers, 9mm wires,24lbs injectors, 190lph fuel pump, MSD cap and rotor, 18" wheels w/street tires

08-24-2001, 12:58 PM	#16
moponys Registered Member Join Date: May 2001 Location: Antioch, CA 94521 Posts: 181	ooohh gotcha... ------------------ TFS twisted wedge heads, TFS street intake, Lunati cam .500/.510 218/226, BBK FPR BBK shorties, BBK 70mm tb, Pro-m 75mm, ASP pulleys, FMS 3:73, Transgo shiftkit Flowmasters, Bassani x-pipe, K&N FIPK, FMS 1.6 roller rockers, 9mm wires,24lbs injectors, 190lph fuel pump, MSD cap and rotor, 18" wheels w/street tires