90GT idle hunting, acceleration stumbling - another take and solution - LONG
04-04-2014, 08:38 PM
#1
Rennlist Member
Thread Starter
90GT idle hunting, acceleration stumbling - another take and solution - LONG
I read Bill Ball's thread on his idle and stumble on acceleration issues with great interest as I was having a very similar problem. I would be sitting at idle, and the motor would intermittently hunt from 600 to 1000 rpm. Then when I'd accelerate away, there would be a stumble and rough spot in acceleration until I would get in a rev range beyond 3000 rpm, and the car would seem to run fine.
I was beginning to think it was the MAF, although I had a rebuilt unit in the car from local 928 Dr. and guru Rich Andrade of Electronik Repair. The GT was acting suspiciously like it did when the MAF was beginning to go out before. At our 928 gathering last weekend here in Phoenix, I was fortunate enough to have to give Rich a ride home, so I gave him the keys to the GT and he noticed the idle hunting and acceleration issues too. Rich thought it could be a failing LH computer... Flash back about 13 years (there are some who've been around here a while that will remember this story, like Rich, Bill Ball and Dr. Bob)...
In 2001, one year after I got my GT, I was very excited to go to my first DEVEK Days. I drove from Phoenix and was halfway between L.A. and San Francisco when I stopped in beautiful Kettlman City for dinner and afterwards the car wouldn't start. Got a hold of Rich on his cell, he put Marc Thomas on the line and they diagnosed a likely LH failure. Marc was gracious enough to leave the Friday evening DEVEK Days welcome reception and drive down to Kettleman City at 1:30 in the morning with a spare LH (compliments of Louie Ott) to save me. We made it back to San Francisco at 4:30 am Saturday morning. I was a bit fuzzy for the days activities and I'm sure Marc was too, but had a great time. I drove home with Louie's loaner LH, but soon needed to send it back to him. I plugged my original LH back in just for fun... and the GT started and ran fine... and had for the past 100k miles!!!
So, last Sunday at Rich's, we swapped in one of his rebuilt LH's and test drove the car. WHAT a difference! No idle hunting, no acceleration flat spot, car ran smooth and strong. I wanted to make sure it was the LH, so Rich let me run his loaner LH for a couple days to confirm that was it. Needless to say, it was definitely the LH computer causing my issues.
I guess with the GT and what's left of its original components being 24 years old, and with the LH having 190k miles on it (100k of that 13 years after we thought it was the culprit in 2001!), I shouldn't be surprised it was the LH. I'm now at the point in ownership with my GT that I'm beginning to repair/replace parts that I've already repaired/replaced like water pumps, radiators, etc. I got my original LH rebuilt by Rich Andrade's Electronik Repair and installed it today. The GT now runs smooth and powerful again.
Thank you Rich, back in 2001 for helping get Marc involved in my rescue, and again today in 2014 for rescuing me again. If any of you are still on your original LH computer, you may not even notice the gradual degradation in performance until it completely gives up. I would highly recommend you get a hold of Rich at Electronik Repair and get your LH rebuilt. It even comes with a 3 year warranty! Although I'm expecting mine to go another 190k miles!!!
I was beginning to think it was the MAF, although I had a rebuilt unit in the car from local 928 Dr. and guru Rich Andrade of Electronik Repair. The GT was acting suspiciously like it did when the MAF was beginning to go out before. At our 928 gathering last weekend here in Phoenix, I was fortunate enough to have to give Rich a ride home, so I gave him the keys to the GT and he noticed the idle hunting and acceleration issues too. Rich thought it could be a failing LH computer... Flash back about 13 years (there are some who've been around here a while that will remember this story, like Rich, Bill Ball and Dr. Bob)...
In 2001, one year after I got my GT, I was very excited to go to my first DEVEK Days. I drove from Phoenix and was halfway between L.A. and San Francisco when I stopped in beautiful Kettlman City for dinner and afterwards the car wouldn't start. Got a hold of Rich on his cell, he put Marc Thomas on the line and they diagnosed a likely LH failure. Marc was gracious enough to leave the Friday evening DEVEK Days welcome reception and drive down to Kettleman City at 1:30 in the morning with a spare LH (compliments of Louie Ott) to save me. We made it back to San Francisco at 4:30 am Saturday morning. I was a bit fuzzy for the days activities and I'm sure Marc was too, but had a great time. I drove home with Louie's loaner LH, but soon needed to send it back to him. I plugged my original LH back in just for fun... and the GT started and ran fine... and had for the past 100k miles!!!
So, last Sunday at Rich's, we swapped in one of his rebuilt LH's and test drove the car. WHAT a difference! No idle hunting, no acceleration flat spot, car ran smooth and strong. I wanted to make sure it was the LH, so Rich let me run his loaner LH for a couple days to confirm that was it. Needless to say, it was definitely the LH computer causing my issues.
I guess with the GT and what's left of its original components being 24 years old, and with the LH having 190k miles on it (100k of that 13 years after we thought it was the culprit in 2001!), I shouldn't be surprised it was the LH. I'm now at the point in ownership with my GT that I'm beginning to repair/replace parts that I've already repaired/replaced like water pumps, radiators, etc. I got my original LH rebuilt by Rich Andrade's Electronik Repair and installed it today. The GT now runs smooth and powerful again.
Thank you Rich, back in 2001 for helping get Marc involved in my rescue, and again today in 2014 for rescuing me again. If any of you are still on your original LH computer, you may not even notice the gradual degradation in performance until it completely gives up. I would highly recommend you get a hold of Rich at Electronik Repair and get your LH rebuilt. It even comes with a 3 year warranty! Although I'm expecting mine to go another 190k miles!!!
04-05-2014, 04:51 AM
#2
Addict
Rennlist Member
Rennlist Member
Rick,
Glad to have helped. I always felt the LH injection module in your GT was living on borrowed time.
You should see another 200K mile out of your GT!
Rich
'93 928 GTS Cover Girl
'87 928 S4
'79 928 5 speed no sun roof rescue
'79 928 Euro track beast
Glad to have helped. I always felt the LH injection module in your GT was living on borrowed time.
You should see another 200K mile out of your GT!
Rich
'93 928 GTS Cover Girl
'87 928 S4
'79 928 5 speed no sun roof rescue
'79 928 Euro track beast
04-05-2014, 10:01 PM
#3
Burning Brakes
Glad to report that Rich rebuilt the LH in my GT last year and my issues (very similar to Rich's above) were addressed as well.
I had a curve ball thrown at me. The ignition circuit relay failed while we were trying to figure out what was going on. Many thanks to Brad Moyer at Digital Chassis in Durham, NC for figuring that one out. And for having a spare in-hand in his shop to ferret out the problem.
I had a curve ball thrown at me. The ignition circuit relay failed while we were trying to figure out what was going on. Many thanks to Brad Moyer at Digital Chassis in Durham, NC for figuring that one out. And for having a spare in-hand in his shop to ferret out the problem.
04-08-2014, 01:34 AM
#4
Rennlist Member
Thread Starter
After driving my GT again today and feeling how smooth and powerful it feels, I just had to bump this in case anybody's missed it. I want to repeat that you often don't realize the performance you're missing as it degrades over time with a weak or failing LH computer. Thanks again to Rich for his diagnosis and saving me hundreds of dollars in parts and time chasing an idle and acceleration problem.
It's been said quite a few times on this list as an easy check... if you're having running issues, try to find someone that has a known good (rebuilt) LH computer that matches your car and swap it in to see if it resolves the issue(s). Could save you a lot of time and money, or at least help narrow the fault possibilities down.
It's been said quite a few times on this list as an easy check... if you're having running issues, try to find someone that has a known good (rebuilt) LH computer that matches your car and swap it in to see if it resolves the issue(s). Could save you a lot of time and money, or at least help narrow the fault possibilities down.
