A Miss..and I am at a total loss...
Discussion
Well, I am at a total loss. I have a higher rpm miss I cannot cure. Here are the symptoms and what I have done to try and fix:
1. Car is 93.5 Esprit. It has the S4s chip, and an exhaust with no cat and a Flowmaster muffler. Everything else is stock.
2. The miss is bizarre. It usually starts at around 4 or 5k RPM, and feels like a cylinder is dropping out. I get a cut in power and a backfire, like a cyliner is not firing and raw gas is hitting the exhaust. Car will not pull to redline.
3. Miss gets worse the longer I run the car. It moves down the RPM band.
4. Miss is worse at full throttle as opposed to half.
5. A few things have cured it temporarily. New plugs. Sitting over night. But, it always comes back after a few hours.
6. One last symptom. Once, I had the interior light on when the miss started. The light would flicker and dim as the car was missing -- like an electrical problem.
What I've changed:
1. Chip and memcal.
2. Spark plugs.
3. Plug wires.
4. Checked the resistance on the TPS.
Any ideas on this one would be appreciated.
Jeff
1. Car is 93.5 Esprit. It has the S4s chip, and an exhaust with no cat and a Flowmaster muffler. Everything else is stock.
2. The miss is bizarre. It usually starts at around 4 or 5k RPM, and feels like a cylinder is dropping out. I get a cut in power and a backfire, like a cyliner is not firing and raw gas is hitting the exhaust. Car will not pull to redline.
3. Miss gets worse the longer I run the car. It moves down the RPM band.
4. Miss is worse at full throttle as opposed to half.
5. A few things have cured it temporarily. New plugs. Sitting over night. But, it always comes back after a few hours.
6. One last symptom. Once, I had the interior light on when the miss started. The light would flicker and dim as the car was missing -- like an electrical problem.
What I've changed:
1. Chip and memcal.
2. Spark plugs.
3. Plug wires.
4. Checked the resistance on the TPS.
Any ideas on this one would be appreciated.
Jeff
Thanks guys. Will freescan it when I have time. Runs ok at normal speeds, so kind of living with it this week.
I thought it was the coils, but I wonder if the alternator is fritzing out at high rpm (and belt speed). The flickering light woudl suggest something like that
On te coil packs, have you changed yours? We started to do it at the track andcould not figure out how the hell to get the bottom nuts/bolts of the pack (the top 2 were hard enough). Any ideas??
I thought it was the coils, but I wonder if the alternator is fritzing out at high rpm (and belt speed). The flickering light woudl suggest something like that
On te coil packs, have you changed yours? We started to do it at the track andcould not figure out how the hell to get the bottom nuts/bolts of the pack (the top 2 were hard enough). Any ideas??
I'm not saying this is the source of your problem but it will only help if you replace the stock coils with MSD coil packs. The MSD coils are a vast improvment over the factory units. There is no need to remove the base that the coils are mounted to. Just remove the two small screws that secure the coil to the base. If you can't see the bottom one try a small mirror. If you need a part # let me know. If I remember, the coils are $40.00 each.
If you need a picture of the two screws just give me a address and I'll zap it over to you.
John
>> Edited by 5150neo on Monday 13th December 09:34
If you need a picture of the two screws just give me a address and I'll zap it over to you.
John
>> Edited by 5150neo on Monday 13th December 09:34
5150neo said:
I'm not saying this is the source of your problem but it will only help if you replace the stock coils with MSD coil packs. The MSD coils are a vast improvment over the factory units. There is no need to remove the base that the coils are mounted to. Just remove the two small screws that secure the coil to the base. If you can't see the bottom one try a small mirror. If you need a part # let me know. If I remember, the coils are $40.00 each.
If you need a picture of the two screws just give me a address and I'll zap it over to you.
John
>> Edited by 5150neo on Monday 13th December 09:34
Are these direct replacements? No need for an MSD-2 box or anything, right?
mine did something similar to this, and the alternator was loose. the little split spacer and the long bolt thats at the top front of the alt. had become loose, was wearing through the casting and it was making the belt go slack/wobbling about, causing all sorts of temporary little voltage problems. when loaded up, it got worse, but it couldnt move too far because it was touching the big curved water pipe. someone had bodged the long bolt holding the alt. on and I re bodged it to make it work. no missfires/idle problems since. well, apart from the standard splutter off of idle that seems quite common. freescan showed the differences before and after. it was only charging at 12-13 volts, now its 13-14V. maybe try this?
Make sure you're map sensor is properly connected. Once, I accidentally pulled the little black tube that runs to it out and I had trouble with the car missing, especially at high throttle. I got a warning code for this but only when the car would quit after idling for a little bit. If you give it gas and keep it going you won't get the check engine light and the code.
Jeff,
I think the fact that your lights dimmed/flicker during the miss says alot.
I would look toward the possibility of the alternator being loose or some sort of electrical short that could be drawing down the available voltage from your coils.
I had a similar problem on a Firebird that I had, as you would jump on the throttle in motion the engine would break up terrible, if you were in park the engine could be reved all day. Turned out to be my positive battery cable was shorting out agains the exhaust header when you torqued up on the engine.
Sometimes it's the simple things that get us;-)
Good luck,
Mike
I think the fact that your lights dimmed/flicker during the miss says alot.
I would look toward the possibility of the alternator being loose or some sort of electrical short that could be drawing down the available voltage from your coils.
I had a similar problem on a Firebird that I had, as you would jump on the throttle in motion the engine would break up terrible, if you were in park the engine could be reved all day. Turned out to be my positive battery cable was shorting out agains the exhaust header when you torqued up on the engine.
Sometimes it's the simple things that get us;-)
Good luck,
Mike
mikelr said:
....Turned out to be my positive battery cable was shorting out agains the exhaust header when you torqued up on the engine.
Sometimes it's the simple things that get us;-)
Good call on that one for a possible place to look Mike. had the same thing happen on my Eclipse but corroded battery terminals were my culrpit. A $3 batery terminal cleaner fixed that problem.
Here's a link to the MSD coils
www.msdignition.com/coil_blaster_9.htm
check ebay too..
>> Edited by jk1 on Tuesday 14th December 20:17
www.msdignition.com/coil_blaster_9.htm
check ebay too..
>> Edited by jk1 on Tuesday 14th December 20:17
Check for low fuel pressure via:
1) a partly blocked fuel filter . . . . a cheap and easy fix works as it out to be a fuel injected Chevy Cavalier (1987?) filter sold at Walmart
2) old and worn-out fuel pumps (primary or secondary) . . . . use Porsche 911 pumps
3) fuel lines with too tight a bend -making a restrictive kink- I replaced all the Lotus stock thin black nylon ones with thick reinforced rubber lines
Just a guess.
AP
1) a partly blocked fuel filter . . . . a cheap and easy fix works as it out to be a fuel injected Chevy Cavalier (1987?) filter sold at Walmart
2) old and worn-out fuel pumps (primary or secondary) . . . . use Porsche 911 pumps
3) fuel lines with too tight a bend -making a restrictive kink- I replaced all the Lotus stock thin black nylon ones with thick reinforced rubber lines
Just a guess.
AP
Check for low fuel pressure via:
1) a partly blocked fuel filter . . . . a cheap and easy fix works as it out to be a fuel injected Chevy Cavalier (1987?) filter sold at Walmart
2) old and worn-out fuel pumps (primary or secondary) . . . . use Porsche 911 pumps
3) fuel lines with too tight a bend -making a restrictive kink- I replaced all the Lotus stock thin black nylon ones with thick reinforced rubber lines
Just a guess.
AP
1) a partly blocked fuel filter . . . . a cheap and easy fix works as it out to be a fuel injected Chevy Cavalier (1987?) filter sold at Walmart
2) old and worn-out fuel pumps (primary or secondary) . . . . use Porsche 911 pumps
3) fuel lines with too tight a bend -making a restrictive kink- I replaced all the Lotus stock thin black nylon ones with thick reinforced rubber lines
Just a guess.
AP
Jeff,
Without me seeing the car I would say that either the wastegate capsule diaphram is disconnected/preforated from the rod or something as simple as the actuator hose has fallen off the turbo wastegate.
When either of these conditions exists the wastegate will fail to bleed off the overboost. The turbo boost will peg on full throttle, then the ECU sensors will detect this over boost (about 1-1.2 bar) cutting the fuel pump pressure to the rail. When this occurs the engine may run lean for a bit and may backfire or the unburned fuel ignite in the cat. More than likely the car will just feel like it is plain running out of gas until the over boost condition goes away. Then fuel pump will then resume full pressure and the engine run fine till the next over boost condition.
Also on full throttle the engine may experience a similar symptom if the plug wires arc or if the plugs are burnt.
I would be inclined to suspect that the hose to waste is off the capsule or has a hole in it as that is pretty common problem and easy to fall off as in most cases it does not has a hose clamp on it, at least the ones I have seen anyways.
Good Luck,
Calvin
Without me seeing the car I would say that either the wastegate capsule diaphram is disconnected/preforated from the rod or something as simple as the actuator hose has fallen off the turbo wastegate.
When either of these conditions exists the wastegate will fail to bleed off the overboost. The turbo boost will peg on full throttle, then the ECU sensors will detect this over boost (about 1-1.2 bar) cutting the fuel pump pressure to the rail. When this occurs the engine may run lean for a bit and may backfire or the unburned fuel ignite in the cat. More than likely the car will just feel like it is plain running out of gas until the over boost condition goes away. Then fuel pump will then resume full pressure and the engine run fine till the next over boost condition.
Also on full throttle the engine may experience a similar symptom if the plug wires arc or if the plugs are burnt.
I would be inclined to suspect that the hose to waste is off the capsule or has a hole in it as that is pretty common problem and easy to fall off as in most cases it does not has a hose clamp on it, at least the ones I have seen anyways.
Good Luck,
Calvin
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