No Computer Codes = Bad Parts? (long)

slo95 · 04-02-2001, 05:22 PM

Yep, Still fighting the rough idle. I had recently installed new cap/rotor/wires/plugs/K&N/ fuel filter, 1 new O2 (only 1 in stock) and cleaned the entire upper intake out, including upper plenum, TB, IAC, and EGR. Previously had a new torque converter installed due to 628 code, excessive slippage. I reset the idle to about 750 in park, and reprogged the computer. All my codes went away for a week. I am getting the 628 AGAIN, and nothing else. The engine DIED (stalled) today at a stop light. Again, No codes. No check engine light (bulb is good).
I also get severe detonation at high RPM's under load, engine warm. Not so much when it is cold. Running 10* timing and 91 Octane fuel.
I read that the EGR can cause idle problems (surge, lope), Converter Slippage, DETONATION, poor mpg, and all sorts of nasty stuff. Can this thing be going bad without codes? it is a 95 GT.
I tried to check the TPS, seemed to change resistance evenly, although I couldnt get an accurate voltage reading, (test leads wouldnt fit) also checked the resistance on the Idle Air Control, it was between the Chiltons spec's at like 900 ohm? I forget, but is was okay...AND the EGR holds a vacuum, and the diaphram moves when "goosed." - it actually idled a little better after messing with the EGR...
Had it at the dealer and they found NO problems, but said they saw/heard the idle problems. Again, this thing stalled on the road today, with no codes. Any Ideas, I am going to start "throwing" money at it with a new EGR, IAC, TPS, ECM, or something, just want to know what first. 87K miles on it.
oh yeah, I cleaned out all the 10 pin and "x number" conectors. this is pretty embarrasing, going off the line with a chevy and having to lay off because of the detonation! thanks in advance...

[This message has been edited by slo95 (edited 04-02-2001).]

slo95 · 04-02-2001, 05:31 PM

One more thing, the engine has been running hotter than normal lately, so hot that the strut tower brace is too hot to touch! That led me to believe the EGR, using exhaust gas, is letting too much hot exhaust into the combustion chambers.

slo95 · 04-03-2001, 11:48 AM

anybody? ttt...

04-03-2001, 02:19 PM

Are you sure your timing is set correctly? If it isn't, it could cause some of your problems.

I would imagine you are experiencing a lean condition, taking the detonation and really hot temps into consideration. I wonder if your fuel pressure regulator is going bad. Or if you have a vacuum leak somewhere. Hook up a fuel guage and look at what it reads at idle and wide open throttle. If that isn't the culprit, then hook up a vacuum guage and see if it is within spec.

This is a start. Post some more info so we can help.

Jason

slo95 · 04-03-2001, 02:32 PM

Thanks, the Timing is at 10*, set at Ford after the new converter install. Still has the nice bright yellow paint on the tick marks so it is EASY to read. I verified w/o spout, and checked for advance with spout. It is okay.
More Info?!, hmmm, didn't really want to BORE anyone more than that first post, but there is really nothing else I can think of, except for the TPS setting. HERE IT IS, also a diff post " I just checked my TPS voltage and resistance, and I think it is arse-backwards...just sitting there, harness unplugged, the resistance on the two lower pins is high, and goes down smoothly as the TB plate opens. BUT the voltage on those pins, KOEO is 4.36vdc closed, and WOT it is at like .48 vdc . can this be right? I always read that it should be around .98 KOEO, and in the 4v at WOT"
I have to get a vacuum and fuel pressure gauge to check those related things, I was kinda holding off to see if a solution would be found BEFORE I dump a hundred bucks on test equipment to then spend more for the fix.

[This message has been edited by slo95 (edited 04-03-2001).]

04-03-2001, 07:16 PM

What other mods do you have done to your car? That is what I meant by details. Just to get an idea of what is causing your grief. I do believe that your TPS is reading backwards. I don't know how this would happen, since if it read 4.98 then when you started your car it would go wot. It happened to me when I put my TPS on backwards. Scared the hell out of me.

slo95 · 04-03-2001, 09:03 PM

gotcha, other mods, well, nothing really -gears, shiftkit, Taylor's and a K&N, thats it. I am all ready to start with the mods, but no way in this condition.
Just rechecked the TPS, helps to probe the correct wires, this time got .953 and 4.67, respectively. that seems okay.
PS, just threw 50 bucks at it, bounced off. New stock FPR, no difference. My main concern is the excessive noise under throttle and load I am getting. I think it is "pinging" but never had a car that pinged so I have no basis. It sounds like a few washers in a tin can being shaken up. only under load, it will not do it in the driveway goosing the throttle.
This is maddening! a Mustang that you cannot get on the gas from the line!

[This message has been edited by slo95 (edited 04-03-2001).]

04-02-2001, 05:22 PM	#1
slo95 Registered Member Join Date: Dec 2000 Posts: 168	No Computer Codes = Bad Parts? (long) Yep, Still fighting the rough idle. I had recently installed new cap/rotor/wires/plugs/K&N/ fuel filter, 1 new O2 (only 1 in stock) and cleaned the entire upper intake out, including upper plenum, TB, IAC, and EGR. Previously had a new torque converter installed due to 628 code, excessive slippage. I reset the idle to about 750 in park, and reprogged the computer. All my codes went away for a week. I am getting the 628 AGAIN, and nothing else. The engine DIED (stalled) today at a stop light. Again, No codes. No check engine light (bulb is good). I also get severe detonation at high RPM's under load, engine warm. Not so much when it is cold. Running 10* timing and 91 Octane fuel. I read that the EGR can cause idle problems (surge, lope), Converter Slippage, DETONATION, poor mpg, and all sorts of nasty stuff. Can this thing be going bad without codes? it is a 95 GT. I tried to check the TPS, seemed to change resistance evenly, although I couldnt get an accurate voltage reading, (test leads wouldnt fit) also checked the resistance on the Idle Air Control, it was between the Chiltons spec's at like 900 ohm? I forget, but is was okay...AND the EGR holds a vacuum, and the diaphram moves when "goosed." - it actually idled a little better after messing with the EGR... Had it at the dealer and they found NO problems, but said they saw/heard the idle problems. Again, this thing stalled on the road today, with no codes. Any Ideas, I am going to start "throwing" money at it with a new EGR, IAC, TPS, ECM, or something, just want to know what first. 87K miles on it. oh yeah, I cleaned out all the 10 pin and "x number" conectors. this is pretty embarrasing, going off the line with a chevy and having to lay off because of the detonation! thanks in advance... [This message has been edited by slo95 (edited 04-02-2001).]

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04-02-2001, 05:31 PM	#2
slo95 Registered Member Join Date: Dec 2000 Posts: 168	One more thing, the engine has been running hotter than normal lately, so hot that the strut tower brace is too hot to touch! That led me to believe the EGR, using exhaust gas, is letting too much hot exhaust into the combustion chambers.

04-03-2001, 11:48 AM	#3
slo95 Registered Member Join Date: Dec 2000 Posts: 168	anybody? ttt...

04-03-2001, 02:19 PM	#4
88GT5.013.02 Guest Posts: n/a	Are you sure your timing is set correctly? If it isn't, it could cause some of your problems. I would imagine you are experiencing a lean condition, taking the detonation and really hot temps into consideration. I wonder if your fuel pressure regulator is going bad. Or if you have a vacuum leak somewhere. Hook up a fuel guage and look at what it reads at idle and wide open throttle. If that isn't the culprit, then hook up a vacuum guage and see if it is within spec. This is a start. Post some more info so we can help. Jason

04-03-2001, 02:32 PM	#5
slo95 Registered Member Join Date: Dec 2000 Posts: 168	Thanks, the Timing is at 10*, set at Ford after the new converter install. Still has the nice bright yellow paint on the tick marks so it is EASY to read. I verified w/o spout, and checked for advance with spout. It is okay. More Info?!, hmmm, didn't really want to BORE anyone more than that first post, but there is really nothing else I can think of, except for the TPS setting. HERE IT IS, also a diff post " I just checked my TPS voltage and resistance, and I think it is arse-backwards...just sitting there, harness unplugged, the resistance on the two lower pins is high, and goes down smoothly as the TB plate opens. BUT the voltage on those pins, KOEO is 4.36vdc closed, and WOT it is at like .48 vdc . can this be right? I always read that it should be around .98 KOEO, and in the 4v at WOT" I have to get a vacuum and fuel pressure gauge to check those related things, I was kinda holding off to see if a solution would be found BEFORE I dump a hundred bucks on test equipment to then spend more for the fix. [This message has been edited by slo95 (edited 04-03-2001).]

04-03-2001, 07:16 PM	#6
88GT5.013.02 Guest Posts: n/a	What other mods do you have done to your car? That is what I meant by details. Just to get an idea of what is causing your grief. I do believe that your TPS is reading backwards. I don't know how this would happen, since if it read 4.98 then when you started your car it would go wot. It happened to me when I put my TPS on backwards. Scared the hell out of me.

04-03-2001, 09:03 PM	#7
slo95 Registered Member Join Date: Dec 2000 Posts: 168	gotcha, other mods, well, nothing really -gears, shiftkit, Taylor's and a K&N, thats it. I am all ready to start with the mods, but no way in this condition. Just rechecked the TPS, helps to probe the correct wires, this time got .953 and 4.67, respectively. that seems okay. PS, just threw 50 bucks at it, bounced off. New stock FPR, no difference. My main concern is the excessive noise under throttle and load I am getting. I think it is "pinging" but never had a car that pinged so I have no basis. It sounds like a few washers in a tin can being shaken up. only under load, it will not do it in the driveway goosing the throttle. This is maddening! a Mustang that you cannot get on the gas from the line! [This message has been edited by slo95 (edited 04-03-2001).]