Hesitation problem fixed!
Thread Starter
Registered User
Joined: Jun 2002
Posts: 548
From: Mantua, NJ, USA
Hesitation problem fixed!
Hopefully this will help others having a hesitation problem:
Symptoms:
The hesitation would occur when the ambient temperature was warm or cold and whether the engine was warm or cold. Extended cranking was usually required to start the car. The car would idle a little rough and would sometimes idle very rough. The car would hesitate when pulling away from a complete stop but would run fine after that. If the car was idling really rough, it would smooth about after a few seconds of driving even while still in open loop mode.
DataMaster Findings:
The LTERM readings (Block Learn) were high. The left was averaging around 152 and the right was at 140. When running the histogram I could see that the computer was detecting a lean condition in all cells. I could not find any air leaks or exhaust leaks. No problems with spark plug wires or plugs causing excess air in the exhaust. The fuel pressure regulator was also fine (41psi at KOEO and 38psi at idle). I also noticed a difference in the fuel injector duty cycle for the left and right side. The left was running at 4.1 and the right 3.9. After implementing the solution, they both are around 1.9 - 2.0.
Cause:
I took the fuel injectors out with the intention of switching sides to see if the readings for the two sides of the engine would follow the injectors. I found the tips of the injectors were really dirty. I cleaned them thoroughly with CARB cleaner and Q-tips and reassembled with the injectors switched to the other side of the engine. The car immediately ran 1000% better. It hasn't run this good in years.
Cost:
$2.50 for the carb cleaner and fuel additive to clean the injectors.
Labor:
1 Hour
It is worth the effort for anybody having hesitation problems to check this out. Hope this helps somebody.
Jeff Muller
Symptoms:
The hesitation would occur when the ambient temperature was warm or cold and whether the engine was warm or cold. Extended cranking was usually required to start the car. The car would idle a little rough and would sometimes idle very rough. The car would hesitate when pulling away from a complete stop but would run fine after that. If the car was idling really rough, it would smooth about after a few seconds of driving even while still in open loop mode.
DataMaster Findings:
The LTERM readings (Block Learn) were high. The left was averaging around 152 and the right was at 140. When running the histogram I could see that the computer was detecting a lean condition in all cells. I could not find any air leaks or exhaust leaks. No problems with spark plug wires or plugs causing excess air in the exhaust. The fuel pressure regulator was also fine (41psi at KOEO and 38psi at idle). I also noticed a difference in the fuel injector duty cycle for the left and right side. The left was running at 4.1 and the right 3.9. After implementing the solution, they both are around 1.9 - 2.0.
Cause:
I took the fuel injectors out with the intention of switching sides to see if the readings for the two sides of the engine would follow the injectors. I found the tips of the injectors were really dirty. I cleaned them thoroughly with CARB cleaner and Q-tips and reassembled with the injectors switched to the other side of the engine. The car immediately ran 1000% better. It hasn't run this good in years.
Cost:
$2.50 for the carb cleaner and fuel additive to clean the injectors.
Labor:
1 Hour
It is worth the effort for anybody having hesitation problems to check this out. Hope this helps somebody.
Jeff Muller
Last edited by SweetZRag; Aug 30, 2004 at 01:32 PM.
Thread Starter
Registered User
Joined: Jun 2002
Posts: 548
From: Mantua, NJ, USA
Re: Hesitation problem fixed!
My signature is current with the miles (262,000 miles) and still runs and looks new now that the hesitation problem is resolved. I have owned it since new and never cleaned them before. I have used a fuel additive injector cleaner on occasion but not for a year or so. The last time I used SeaFoam. I will be using a cleaner more often, you can bet on that!
Thread Starter
Registered User
Joined: Jun 2002
Posts: 548
From: Mantua, NJ, USA
Re: Hesitation problem fixed!
It may not solve all of the hesitation problems I have seen on this forum but it is good maintenance and it cost nothing to eliminate one variable from your list of causes. Good luck...
Holy crap you've got that many miles on your Z. Thats the most Ive ever seen. Way to maintain your ride!
Thread Starter
Registered User
Joined: Jun 2002
Posts: 548
From: Mantua, NJ, USA
Re: Hesitation problem fixed!
I don't think I have seen anyone with more miles either. The car is my wife's daily driver. I don't let anyone touch the car but me so I know it is maintained correctly. The beauty is that it looks new, even the convertible top (garage kept).
I looked for a cleaner that said CARB & Injector cleaner. I pulled the injectors out and sprayed cleaner in both ends of the injector. I used Q tips to wipe away the loosened gunk from the spraying end. My wife has these special Q tips that are wound extra tight and come to a point. They are used for applying makeup. They worked really well but the regular ones should be fine too.
It has been a couple of weeks and she tells me the car has never been better. She says this problem must have been gradually building for years so she didn't notice it. Since I rarely get to drive it, I didn't notice it until it got bad.
I am hoping this helps some people although I realize there could be many causes of hesitation. Good luck with yours!
I looked for a cleaner that said CARB & Injector cleaner. I pulled the injectors out and sprayed cleaner in both ends of the injector. I used Q tips to wipe away the loosened gunk from the spraying end. My wife has these special Q tips that are wound extra tight and come to a point. They are used for applying makeup. They worked really well but the regular ones should be fine too.
It has been a couple of weeks and she tells me the car has never been better. She says this problem must have been gradually building for years so she didn't notice it. Since I rarely get to drive it, I didn't notice it until it got bad.
I am hoping this helps some people although I realize there could be many causes of hesitation. Good luck with yours!
Registered User
Joined: May 2002
Posts: 289
From: Fort Collins, Colorado
Re: Hesitation problem fixed!
In a somewhat breif method, how would one go about pulling the injectors? I looked at it..and it seems like you have to relieve the fuel pressure with the shradder/shroudder valve (is that right?) and then pull all kinds of stuff off.. 
I dont have any pressure gauges or anything..so I cant test pressures and stuff...I just want to clean them since the car is under the knife for a few weeks anyways. Are the fuel rails easy to pull off without moving too many other things and does fuel leak from anywhere when unbolting it? Since you were gonna swap sides anyways, does it matter how they go in? I take it all 8 are prefectly equal and can go into any cylinder port on the fuel rail? Thanks man, good info too! and thats insane..I think Chevy should do a commercial for your wife's car and give you a newer Camaro 
Thats what a friends dad did..(he was rich anyways..lol)..but he had an 87' Supra that had over 375,000 miles on it..they GAVE him a non-turboed brand new Supra to do a commercial on T.V. for it.Anyways, thanks in advance! Derek
I dont have any pressure gauges or anything..so I cant test pressures and stuff...I just want to clean them since the car is under the knife for a few weeks anyways. Are the fuel rails easy to pull off without moving too many other things and does fuel leak from anywhere when unbolting it? Since you were gonna swap sides anyways, does it matter how they go in? I take it all 8 are prefectly equal and can go into any cylinder port on the fuel rail? Thanks man, good info too! and thats insane..I think Chevy should do a commercial for your wife's car and give you a newer Camaro Thats what a friends dad did..(he was rich anyways..lol)..but he had an 87' Supra that had over 375,000 miles on it..they GAVE him a non-turboed brand new Supra to do a commercial on T.V. for it.Anyways, thanks in advance! Derek
Registered User
Joined: Aug 2002
Posts: 2,325
From: BC
Re: Hesitation problem fixed!
Injectors are a snap, just no smoking
Step 1 - Relieve pressure at schrader. I used my fuel pressure guage, but you can use a big rag and press the pin in to relieve it. Do this when the engine is cold.
Step 2 - Remove the injector wires from the injectors. Just push the clip in and it should slide right off. Theyre all numbered on the sides.
Step 3 - Remove 4 bolts on the fuel rail.
Step 4 - Carefully with a big wide screwdriver pry up on the fuel rail. I used the small tube between the two sides and carefully inched it up by switching from side to side.
Step 5 - Carefully Pull off each injector.
Step 6 - Clean injectors up, and just do steps 5-1 backwards.
I'd recommend professional cleaning. BUT if your on a budget and youve never cleaned them before it really can't hurt unless your careless...
Step 1 - Relieve pressure at schrader. I used my fuel pressure guage, but you can use a big rag and press the pin in to relieve it. Do this when the engine is cold.
Step 2 - Remove the injector wires from the injectors. Just push the clip in and it should slide right off. Theyre all numbered on the sides.
Step 3 - Remove 4 bolts on the fuel rail.
Step 4 - Carefully with a big wide screwdriver pry up on the fuel rail. I used the small tube between the two sides and carefully inched it up by switching from side to side.
Step 5 - Carefully Pull off each injector.
Step 6 - Clean injectors up, and just do steps 5-1 backwards.
I'd recommend professional cleaning. BUT if your on a budget and youve never cleaned them before it really can't hurt unless your careless...
Registered User
Joined: May 2002
Posts: 289
From: Fort Collins, Colorado
Re: Hesitation problem fixed!
So would it be smart to help relieve pressure by opening the gas cap? Also, whats the best cleaning agent? Anything that says carburator/injector cleaner? Lastly, so by bleeding/relieving the pressure, no fuel will come out anywhere else right?