LongDuck

Just a quick report on an issue that I may have identified a cause for this past weekend that's specific to GSL-SE's in 84/85 and reported by several users here.

Problem: Occasionally, and seemingly randomly, the engine seems to lose significant power and the exhaust note turns to a 'thumpy' idle, if it will idle at all. The engine vibration is seriously out of whack and the car is barely driveable. This has been referred to as 'Single Rotor' operation in the past, where it seems that the engine is only firing on one rotor due to spark/fuel/MAF, whatever, and is hard to diagnose. When the car is functioning in this mode, it will not rev up correctly, and large amounts of accelerator pedal are required to keep it running at all.

Previous fix: turning the car off and then back on seemed to fix this problem about half the time, though some users reported this as an ongoing problem that eventually cleared itself up.

My findings: this past weekend, while getting pizza for dinner, I drove several miles to the local kitchen and picked up a pizza (waited about 10 minutes with the car turned off). On restart, the engine immediately went into Single Rotor mode and the idle was horrible, no power, and not driveable to get me home. I pulled into a parking spot and popped the hood.

Since I've been messing around with a bad injector for the past several weeks, I figured this was just the injector acting up, but was definitely more than an overly rich mixture at idle, which goes away under acceleration due to more air making it in and getting closer to the 14.7/1 proper a/f ration. In any case, I stared pulling on the wiring harness that goes to the fuel injectors and oxygen sensor and immediately, the idle returned to normal (2 rotor operation again). Moving the wiring harness again, and pushing slack into the injector connectors, the engine went back to Single Rotor. I could replicate this many times just by moving the wiring harness back and forth, which lead me to believe that it's the cable harness either at the injector interface, or the wiring in between there and the 'split' at the main harness.

To be sure you know the harness I'm talking about, it runs directly behind the alternator on the SE's and splits off into the BCAV valve on the drivers side, and on the passenger side includes both connectors for the fuel injectors and Oxygen sensor, and goes down toward the emission control devices and MAF on the passenger front.

This harness could be moved behind the water pump and enact the changes listed above. For confirmation, if another member of the group has the Single Rotor operation problem and tries to move the cabling as described, this may help to identify a known problem with either the wiring harness or with the injector connector(s).

I will be taking my intake manifold apart tonight to install my replacement injector and report back with what I find. Hopefully, it's just a loose connector and not a broken wire in the bundle.

Anybody else experience this, or have a fix that they've used??? HTH, and TIA

j9fd3s

iTrader: (3)

i had one of the pins pull out of the injector connector once, it sounds like you have something similar or a bad wire. it sould be easy to find, you already know where to look

mike

Forseti

Can't say I've had the same issue. But thanks for documenting it. Right now I just have a high idle, and I've tried everything except mucking with the mixture. Who know...maybe I have a bad wire somewhere too.

So your injector was not the problem in the first place?

F-

spoolin

i'll keep this in mind as i just bought two more 1st gens.....one is an ocean blue metallic GSL-SE and the other will be my 13B bridgeport

LongDuck

BAP received the new, replacement injector last night and I haven't taken the time to put it in to figure out if that's the true problem (poor idle, stumbles off idle, and surges at steady state driving on freeway).

My guess is that it's a badly rebuilt injector, but will install tonight or tomorrow and report back.

While I have it all apart, I'm going to be troubleshooting the injector cables to see if there's an intermittent short or possibly just a bad connector.

Anyone know where I can get a new injector socket that I can splice into the harness? TIA,

j9fd3s

iTrader: (3)

you can buy injector connectors from lot of places
pep boys has them
so does hks

mike

j9fd3s

iTrader: (3)

when its idling high press down on the tps adjuster screw. if the idle speed goes down, its the throttle body sticking.

mike

Forseti

j9fd: Thanks for the tip I'll try it. I have completely removed and cleaned my TB, and have also tried to lube the linkages.

I had idle issues before cycling surging that I solved by cleaning the TB.

Once I did that , it used to idle at 800 perfectly. However, when I got it back from having a new tranny put it, it has idled high but consistently, sometimes at 900, sometimes at 1000.

I'm assuming pushing down on the tps screw will close the plates completely. I'll give it a try.

Thx,
F-

Forseti

j9...yep I could hear it drop...wasn't able to look in the car at the same time.. Wonder if there's a way I can fix it without replacing the TB.

I have cleaned it a number of times and tried to lube the inside hinges and linkages with wd-40.

Suggestions would be appreciated.

F-