Hesitation off idle
Registered User
Joined: Oct 2002
Posts: 23
From: NJ
Re: SOLVED!
Originally posted by HungryT/A
Sorry folks to bring back this ol' tread, but I do think many of you are still chasing the infamous low rpm (1000-2000) stumble.
THE PROBLEM IS GONE, HELL YEAH!
After houndreds and houndreds of $$$$$$, many sleepless nights and f*cked up afternoons wrenching under the car, ...
guess what was the problem....!
INJECTORS!!!!
After changing the plugs, some were showing sings of being extremely rich. Some were even "wet". Opened the TB it smelled gas.
We made a datamester log to capture "the moment". To make a long story short, during the 1000-2000 rpm range, when stomped, the engine was practically flooded with fuel. We could even catch an exhaust backfiring and record it on Datamaster
I replaced them with #30 Accel's, GOD, what a difference. And I think Accel isn't even the best brand
Sorry folks to bring back this ol' tread, but I do think many of you are still chasing the infamous low rpm (1000-2000) stumble.
THE PROBLEM IS GONE, HELL YEAH!
After houndreds and houndreds of $$$$$$, many sleepless nights and f*cked up afternoons wrenching under the car, ...
guess what was the problem....!
INJECTORS!!!!
After changing the plugs, some were showing sings of being extremely rich. Some were even "wet". Opened the TB it smelled gas.
We made a datamester log to capture "the moment". To make a long story short, during the 1000-2000 rpm range, when stomped, the engine was practically flooded with fuel. We could even catch an exhaust backfiring and record it on Datamaster
I replaced them with #30 Accel's, GOD, what a difference. And I think Accel isn't even the best brand
but isn't it really bad if the engine is flooded with fuel???
Registered User
Joined: Oct 2002
Posts: 22
well.. my problem was intermiting but it was definatly hesistate, and sometimes not even crank or take a while to crank.. it was also surge.. I have notice this onece since the new fuel pump this is nearly 6 months later but I added gas to my tank and it fixed it.. dunno if the gauge was that off (showed 1/4) or if the pump was having trouble pumping...
Registered User
Joined: Feb 2003
Posts: 569
From: South Dakota
I know that these are old posts, but I am hoping that someone is still reading them and that this may help. You say that you do not get the hestiation until the car is warmed up? How many of you have done a TB byapss and still have the problem. I had a rough idle at idle and a slight hestation when I bought my '95 Z, and right away I replaced the fuel filter, plugs, and coil. I had the same problem, so I decided to do the TB bypass. Now the low idle miss and the hestation is gone! You may also want to look into an adjustable FPR, some of these cars are running VERY rich for the altitude variations. I read about a guy that actually LOWERED his pressure from 43psi to 37psi and picked up 16RWHP!! I know that this is obviously not true for everone, but that's what experimentation is for. Also, I read of someone having a problem at high RPM's. You may want check your timing and see if it is being retarded by the PCM, and if so, I would definately put in an LT4 KM that will take care of it.
Happy hunting!!
Happy hunting!!
Registered User
Joined: Feb 2003
Posts: 569
From: South Dakota
After reading a few more posts, I came to the question of the cam in the LT1. What are its EXACT specs, and what RPM range was it created for? I know that the LT1 can rev fairly high, and in consequence you sacrifice off idle power. Also, heat is definately an issue with these cars. They are "designed" to operate at high temps simply because the tree huggers got their meathooks into the car industry. I'm not saying that it was for the wrong reasons, and after living in Cali you sure do appreciate emssions standards. The electronics in the LT1 are solid state, and majoring in electronics, you learn right away that heat is the number 1 enemy of these devices. This leads to the TPS and the ECM. They are both mounted on ares of the engine that are subject to high temps (TPS on TB-yes hot coolant does flow through there, ECM-on the head, that's a no-brainer). Once these electronics are subjected to these temps, after time, they begin to lose tolerance, which in turn makes them less responsive, etc. The only thing that you can do is experiment and see what gets it working for you!
Registered User
Joined: Nov 2000
Posts: 166
From: miami fl us
Originally posted by hairbear21
After reading a few more posts, I came to the question of the cam in the LT1. What are its EXACT specs, and what RPM range was it created for? I know that the LT1 can rev fairly high, and in consequence you sacrifice off idle power. Also, heat is definately an issue with these cars. They are "designed" to operate at high temps simply because the tree huggers got their meathooks into the car industry. I'm not saying that it was for the wrong reasons, and after living in Cali you sure do appreciate emssions standards. The electronics in the LT1 are solid state, and majoring in electronics, you learn right away that heat is the number 1 enemy of these devices. This leads to the TPS and the ECM. They are both mounted on ares of the engine that are subject to high temps (TPS on TB-yes hot coolant does flow through there, ECM-on the head, that's a no-brainer). Once these electronics are subjected to these temps, after time, they begin to lose tolerance, which in turn makes them less responsive, etc. The only thing that you can do is experiment and see what gets it working for you!
After reading a few more posts, I came to the question of the cam in the LT1. What are its EXACT specs, and what RPM range was it created for? I know that the LT1 can rev fairly high, and in consequence you sacrifice off idle power. Also, heat is definately an issue with these cars. They are "designed" to operate at high temps simply because the tree huggers got their meathooks into the car industry. I'm not saying that it was for the wrong reasons, and after living in Cali you sure do appreciate emssions standards. The electronics in the LT1 are solid state, and majoring in electronics, you learn right away that heat is the number 1 enemy of these devices. This leads to the TPS and the ECM. They are both mounted on ares of the engine that are subject to high temps (TPS on TB-yes hot coolant does flow through there, ECM-on the head, that's a no-brainer). Once these electronics are subjected to these temps, after time, they begin to lose tolerance, which in turn makes them less responsive, etc. The only thing that you can do is experiment and see what gets it working for you!
I think you have the ecm mixed up with the coil.
Registered User
Joined: Jun 2003
Posts: 90
From: CP, NY
Re: SOLVED!
Originally posted by HungryT/A
Sorry folks to bring back this ol' tread, but I do think many of you are still chasing the infamous low rpm (1000-2000) stumble.
THE PROBLEM IS GONE, HELL YEAH!
After houndreds and houndreds of $$$$$$, many sleepless nights and f*cked up afternoons wrenching under the car, ...
guess what was the problem....!
INJECTORS!!!!
After changing the plugs, some were showing sings of being extremely rich. Some were even "wet". Opened the TB it smelled gas.
We made a datamester log to capture "the moment". To make a long story short, during the 1000-2000 rpm range, when stomped, the engine was practically flooded with fuel. We could even catch an exhaust backfiring and record it on Datamaster
I replaced them with #30 Accel's, GOD, what a difference. And I think Accel isn't even the best brand
Good luck to all of you!
Sorry folks to bring back this ol' tread, but I do think many of you are still chasing the infamous low rpm (1000-2000) stumble.
THE PROBLEM IS GONE, HELL YEAH!
After houndreds and houndreds of $$$$$$, many sleepless nights and f*cked up afternoons wrenching under the car, ...
guess what was the problem....!
INJECTORS!!!!
After changing the plugs, some were showing sings of being extremely rich. Some were even "wet". Opened the TB it smelled gas.
We made a datamester log to capture "the moment". To make a long story short, during the 1000-2000 rpm range, when stomped, the engine was practically flooded with fuel. We could even catch an exhaust backfiring and record it on Datamaster
I replaced them with #30 Accel's, GOD, what a difference. And I think Accel isn't even the best brand
Good luck to all of you!
what are the stock injectors rated at??
Registered User
Joined: Aug 2002
Posts: 183
From: Long Island, New York
Originally posted by tubby
guys that don't have this problem just don't understand. try this unplug your MAF. i did this tonight. immediately i gained back my instantanious throttle repsonse. so i plugged it back in still seemed good. (scratching head). so i decided to clean MAF with electronics cleaner. let it warm up even more, hestitation was back. unplugged MAF hestitation gone. plugged it back in still gone???? now i do have autotap but i don't know how to test this to show the difference. this is just listening to the motor.
guys that don't have this problem just don't understand. try this unplug your MAF. i did this tonight. immediately i gained back my instantanious throttle repsonse. so i plugged it back in still seemed good. (scratching head). so i decided to clean MAF with electronics cleaner. let it warm up even more, hestitation was back. unplugged MAF hestitation gone. plugged it back in still gone???? now i do have autotap but i don't know how to test this to show the difference. this is just listening to the motor.
Registered User
Joined: Aug 2002
Posts: 2,325
From: BC
Unplug the maf with the car OFF then turn her back on without it hooked up. The SES light will come on, and it should be referring to the tables for the MAF readings now.
An update on my MAF cleaning....
I cleaned my MAF and the hesitation completly (well 95%)disappeared for - a day or so
Now its back and just as bad as before, no idea why! When I run the car with the MAF unplugged the hesitation still happens. 
Why on earth would it go away for a day after cleaning and then come back? I must have some other sensor messed up.... need to get this car scanned :/
An update on my MAF cleaning....
I cleaned my MAF and the hesitation completly (well 95%)disappeared for - a day or so
Now its back and just as bad as before, no idea why! When I run the car with the MAF unplugged the hesitation still happens. Why on earth would it go away for a day after cleaning and then come back? I must have some other sensor messed up.... need to get this car scanned :/
Registered User
Joined: Jul 2003
Posts: 98
I also have had this problem since I bought the car.. I know the owners before knew it had this problem also.. you woulda thought theyd tell me about it before selling it.. oh well.. I took it in about a year ago to have it totally checked out.. all liquids drained wires/plugs changed/fuel filter changed, compression checks, scanned, pretty much everything.. and it still has this stumble/hesitation when it warms up.. it runs likea beast when cold though.. I wish I could get it fixed because I love my car when I first start it.. its just after I cruise for a little i hate it and don'tw ant to drive it anymore.. grr.. I have also noticed that the 2k is my hesitation line too.. its really friggin wierd..
