3k RPM hesitation - INTERESTING !
10-14-03, 02:49 PM
#1
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3k RPM hesitation - INTERESTING !
I wanted to write this up a while ago, but I kept forgetting to do so 
Well, I just wanted everyone to know that with my euro stock ECU I didn't have any 3k RPM hesitation and after installing non-Cali M2 stage3 ECU from '93 car I'm getting 3k RPM hesitation.
It doesn't bother me much, but just wanted to share it with everyone who were looking for sources of this hesitation. It's in the ECU apparently...
Well, I just wanted everyone to know that with my euro stock ECU I didn't have any 3k RPM hesitation and after installing non-Cali M2 stage3 ECU from '93 car I'm getting 3k RPM hesitation.
It doesn't bother me much, but just wanted to share it with everyone who were looking for sources of this hesitation. It's in the ECU apparently...
10-14-03, 03:34 PM
#2
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don't you just love that hesitation. i thought it had to do with needing better grounding. that's what cured my problem. do you have any kind of aftermarket/do-it-yourself grounding in your car?
10-14-03, 03:56 PM
#3
Originally posted by Tanabe
don't you just love that hesitation. i thought it had to do with needing better grounding. that's what cured my problem. do you have any kind of aftermarket/do-it-yourself grounding in your car?
don't you just love that hesitation. i thought it had to do with needing better grounding. that's what cured my problem. do you have any kind of aftermarket/do-it-yourself grounding in your car?
10-14-03, 09:14 PM
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Originally posted by Godzilla-T78
i removed my vacumme system from the car for the stock twins.. that solved mine.
i removed my vacumme system from the car for the stock twins.. that solved mine.
10-14-03, 09:45 PM
#7
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i also remember that when i switched to non-seq i had no hesitation. I don't think it's ground related as i have around 10 grounds and i still get it. I do however think it's related to either fuel pump or injectors the way they come on line. I also noticed every time i get fuel cut, my shitty a/f gauge goes to lean and then back up to rich.
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10-14-03, 10:00 PM
#8
fart on a friends head!!!
Originally posted by BoOsTin FD
i also remember that when i switched to non-seq i had no hesitation. I don't think it's ground related as i have around 10 grounds and i still get it. I do however think it's related to either fuel pump or injectors the way they come on line. I also noticed every time i get fuel cut, my shitty a/f gauge goes to lean and then back up to rich.
i also remember that when i switched to non-seq i had no hesitation. I don't think it's ground related as i have around 10 grounds and i still get it. I do however think it's related to either fuel pump or injectors the way they come on line. I also noticed every time i get fuel cut, my shitty a/f gauge goes to lean and then back up to rich.
paul
10-14-03, 10:46 PM
#9
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there was a big explanation for this, damian wrote i believe. check the archives...its something to do with the fuel pump switching from 10v to 12v at 3000rpm or sooomething like that.
10-15-03, 03:25 AM
#12
im going to third that its the ECU. when i first bought my car i had the bucking problem with a non cali ecu. i then bought a PFC and the hesitation stopped. time for smog i borrowed a friends ECU(couldnt find mine) and the hesitation was back. PFC is back in and it works like a charm.
another thought could be the four wires that are emission related for the PFC. those are the only wires that are messed with when going from stock ECU to PFC. im still going to side with the stock ECU is junk.
kris
another thought could be the four wires that are emission related for the PFC. those are the only wires that are messed with when going from stock ECU to PFC. im still going to side with the stock ECU is junk.
kris
10-15-03, 03:43 AM
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Once someone told me that US ECU pins that control the EGR (euro FDs don't have it) control the Fuel Pressure Regulator in euro FDs. Could it be the fuel pressure drop that is causing that hesitation ?
10-15-03, 12:47 PM
#14
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This isn't anything new - it's been known for a LONG time that it's a quirk in the ECU's programming that causes the 3000 RPM hesitation. Adding a ground strap from the negative battery terminal to frame helps a LOT, some more than others.
That's one of the best things about the PowerFC - the hesitation is totally gone.
Dale
That's one of the best things about the PowerFC - the hesitation is totally gone.
Dale
10-15-03, 01:10 PM
#15
Originally posted by dcfc3s
This isn't anything new - it's been known for a LONG time that it's a quirk in the ECU's programming that causes the 3000 RPM hesitation.
This isn't anything new - it's been known for a LONG time that it's a quirk in the ECU's programming that causes the 3000 RPM hesitation.
Also, the cars didn't roll off the assembly line with the problem so the ECU simply cannot be the source.
10-15-03, 03:16 PM
#17
No it's not Turbo'd
The ECU from all accounts I've heard has a 32K Mi. break in period... at which point it changes the way it delivers fuel and spark, supposedly... that with possibly worn out injectors, or possibly a more subtle change at 60K mi. would account for the ECU not beeing faulty in the beginning but having symptoms later on...
How many miles on each ECU !?
How many miles on each ECU !?
10-15-03, 03:54 PM
#18
I've recently talked to someone and they also told me about this mileage thing.. But I heard that miles are all located on the speedo.. So, if your speedo reads 40K+ and your ecu is brand new, It will re-program..
This source of information was very good one..
Anyhow, I could also say that its the ECU.. I had 93 Base ECU.. had the 3K.. switched to M2stage 3 Cali ECU 1993.. I had 3k hesitation.. I switched to PFC.. Idled better and no 3k hesitation.. switched from M2 to PFC.. no mods were made.. just ecu..
This source of information was very good one..
Anyhow, I could also say that its the ECU.. I had 93 Base ECU.. had the 3K.. switched to M2stage 3 Cali ECU 1993.. I had 3k hesitation.. I switched to PFC.. Idled better and no 3k hesitation.. switched from M2 to PFC.. no mods were made.. just ecu..
10-15-03, 04:06 PM
#19
Originally posted by DCrosby
The ECU from all accounts I've heard has a 32K Mi. break in period... at which point it changes the way it delivers fuel and spark, supposedly... that with possibly worn out injectors, or possibly a more subtle change at 60K mi. would account for the ECU not beeing faulty in the beginning but having symptoms later on...
How many miles on each ECU !?
The ECU from all accounts I've heard has a 32K Mi. break in period... at which point it changes the way it delivers fuel and spark, supposedly... that with possibly worn out injectors, or possibly a more subtle change at 60K mi. would account for the ECU not beeing faulty in the beginning but having symptoms later on...
How many miles on each ECU !?
IMO, the PFC and other aftermarket ECU's just bandaid the problem so it's not "as noticeable". I would put my money more on old/worn out components such as the various soleniods (some of which aftermarket ECU's ignore which would explain why they lessen/rid the car of the hesitation if that were the problem).
10-15-03, 04:15 PM
#20
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its from the way the stock fuel pump switches from low to high. If you really want to get rid of it, redo ALL your grounds, not just the fuel pump ground, and upgrade your fuel pump along with the PFC. You wont have it after that! 
10-15-03, 05:45 PM
#22
I added a battery to frame and bat to engine ground on my 7. This made a noticeable difference. However my hesitation has definitely not left.
I’ve read some threads that blame a sort of valve cracking or wearing out in the fuel pump, grounds, the fuel pump not transitioning from high to low quick enough, different ECU firmware versions, etc. I think that any of these are reasonable explanations but no single one is the silver bullet. That is there are probably several possible explanations outside of the ECU.
My current theory (in my car) is that the ECU isn’t supplied enough current to properly open the secondary set of injectors (around 3K RPMs). Once the inrush current of opening the secondarys is over with everything is OK. If this is true, why does the hesitation not exist under heavy boost? I don’t know. I haven’t had the change to track down the positive and negative (other than ECU case ground) power inputs to the ECU. When I do have a chance, I’m going to buffer the inputs with a large capacitor … something similar to what is done on high powered stereo amps. It’s just a guess … I may find nothing or it may solve it for me. I’ve read threads where a fuel pressure gauge gave away the fuel pump valve problem and others that showed perfect fuel pressure during the hesitation. What I’m saying is that there are probably several problems that cause the hesitation … much like the sequential turbo system malfunctions in so many ways.
I’ve read some threads that blame a sort of valve cracking or wearing out in the fuel pump, grounds, the fuel pump not transitioning from high to low quick enough, different ECU firmware versions, etc. I think that any of these are reasonable explanations but no single one is the silver bullet. That is there are probably several possible explanations outside of the ECU.
My current theory (in my car) is that the ECU isn’t supplied enough current to properly open the secondary set of injectors (around 3K RPMs). Once the inrush current of opening the secondarys is over with everything is OK. If this is true, why does the hesitation not exist under heavy boost? I don’t know. I haven’t had the change to track down the positive and negative (other than ECU case ground) power inputs to the ECU. When I do have a chance, I’m going to buffer the inputs with a large capacitor … something similar to what is done on high powered stereo amps. It’s just a guess … I may find nothing or it may solve it for me. I’ve read threads where a fuel pressure gauge gave away the fuel pump valve problem and others that showed perfect fuel pressure during the hesitation. What I’m saying is that there are probably several problems that cause the hesitation … much like the sequential turbo system malfunctions in so many ways.
10-15-03, 06:20 PM
#23
I'm not the first person to suggest this, but the 3K hesitation seems to be the result of a number of different factors, and may even have totally different causes from car to car.
I had the 3K hesitation for a long time. I got a PowerFC and it was totally gone and I never had it again. The PowerFC seems to be a sure-fire solution. My car drove MUCH better after the PowerFC install.
But that doesn't mean that the ECU is the only cause. It could be several other factors that all "conspire" with the ECU to give you a hesitation. You might put that same ECU into another car and it would have no hesitation because the other circumstances aren't there to give the hesitiation.
Grounding has been a highly touted solution for a long time. It did not work on my car in the long term. I believe that many of the ground strap success stories are the result of someone resetting the ECU by disconnecting the ground terminal from the battery while working on the car and then declaring success when they hook everything back up and the hesitation is gone or reduced. After the ECU has a little time to (mal)adapt to the car again, the hesitation comes back. But you don't see many of those posts -- its no fun to report the return of a gremlin. And then again, bad grounds may be one of the conspititors in some instances of the hesitiation and it is possible that the ground strap really does fix it. But ground straps did not provide a lasting fix on my car.
-Max
I had the 3K hesitation for a long time. I got a PowerFC and it was totally gone and I never had it again. The PowerFC seems to be a sure-fire solution. My car drove MUCH better after the PowerFC install.
But that doesn't mean that the ECU is the only cause. It could be several other factors that all "conspire" with the ECU to give you a hesitation. You might put that same ECU into another car and it would have no hesitation because the other circumstances aren't there to give the hesitiation.
Grounding has been a highly touted solution for a long time. It did not work on my car in the long term. I believe that many of the ground strap success stories are the result of someone resetting the ECU by disconnecting the ground terminal from the battery while working on the car and then declaring success when they hook everything back up and the hesitation is gone or reduced. After the ECU has a little time to (mal)adapt to the car again, the hesitation comes back. But you don't see many of those posts -- its no fun to report the return of a gremlin. And then again, bad grounds may be one of the conspititors in some instances of the hesitiation and it is possible that the ground strap really does fix it. But ground straps did not provide a lasting fix on my car.
-Max
10-15-03, 08:44 PM
#24
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well Said Max, I totally agree with you, I just hope that someone could come up with cheaper solution to fix it rather than spending money on PFC which i can't afford right now.
Originally posted by maxcooper
I'm not the first person to suggest this, but the 3K hesitation seems to be the result of a number of different factors, and may even have totally different causes from car to car.
I had the 3K hesitation for a long time. I got a PowerFC and it was totally gone and I never had it again. The PowerFC seems to be a sure-fire solution. My car drove MUCH better after the PowerFC install.
But that doesn't mean that the ECU is the only cause. It could be several other factors that all "conspire" with the ECU to give you a hesitation. You might put that same ECU into another car and it would have no hesitation because the other circumstances aren't there to give the hesitiation.
Grounding has been a highly touted solution for a long time. It did not work on my car in the long term. I believe that many of the ground strap success stories are the result of someone resetting the ECU by disconnecting the ground terminal from the battery while working on the car and then declaring success when they hook everything back up and the hesitation is gone or reduced. After the ECU has a little time to (mal)adapt to the car again, the hesitation comes back. But you don't see many of those posts -- its no fun to report the return of a gremlin. And then again, bad grounds may be one of the conspititors in some instances of the hesitiation and it is possible that the ground strap really does fix it. But ground straps did not provide a lasting fix on my car.
-Max
I'm not the first person to suggest this, but the 3K hesitation seems to be the result of a number of different factors, and may even have totally different causes from car to car.
I had the 3K hesitation for a long time. I got a PowerFC and it was totally gone and I never had it again. The PowerFC seems to be a sure-fire solution. My car drove MUCH better after the PowerFC install.
But that doesn't mean that the ECU is the only cause. It could be several other factors that all "conspire" with the ECU to give you a hesitation. You might put that same ECU into another car and it would have no hesitation because the other circumstances aren't there to give the hesitiation.
Grounding has been a highly touted solution for a long time. It did not work on my car in the long term. I believe that many of the ground strap success stories are the result of someone resetting the ECU by disconnecting the ground terminal from the battery while working on the car and then declaring success when they hook everything back up and the hesitation is gone or reduced. After the ECU has a little time to (mal)adapt to the car again, the hesitation comes back. But you don't see many of those posts -- its no fun to report the return of a gremlin. And then again, bad grounds may be one of the conspititors in some instances of the hesitiation and it is possible that the ground strap really does fix it. But ground straps did not provide a lasting fix on my car.
-Max
10-20-03, 06:48 PM
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I have the dreaded hesitation. Along with this, I noticed that I have a surging and the A/F mixture goes lean, then rich at the same time. This happens at all RPM's but mainly noticeable in first gear at around 5K. Then under light accelleration at 2.5K to 3K, the car starts bucking in 2nd gear. Under normal or moderate accelleration, the hesitation occurs normally at 3K, then solid on up the spectrum.
I will be buying a brand new battery tomorrow (Optima red top) and installing it first. Reason is that the ground connection on the current battery is not good even though the bolt is tight. I tried eliminating the inline 1K resistor for the fuel pump and thought I noticed a smoother difference, but still have the hesitation. After this, I will put all the ground wires from the computer through the firewall to the engine, to the negative terminal.
If this does not work, there is a pressure regulator relay that bumps up pressure at startup and hot starts. I am going to bypass that to increase fuel pressure.
All of these things seem like possible logical fixes, but like someone already said, there are different problems with different cars. Not all of them may respond the same to the same solutions.
Tim
I will be buying a brand new battery tomorrow (Optima red top) and installing it first. Reason is that the ground connection on the current battery is not good even though the bolt is tight. I tried eliminating the inline 1K resistor for the fuel pump and thought I noticed a smoother difference, but still have the hesitation. After this, I will put all the ground wires from the computer through the firewall to the engine, to the negative terminal.
If this does not work, there is a pressure regulator relay that bumps up pressure at startup and hot starts. I am going to bypass that to increase fuel pressure.
All of these things seem like possible logical fixes, but like someone already said, there are different problems with different cars. Not all of them may respond the same to the same solutions.
Tim