86 930 not running right

k930 · 03-19-2022, 03:59 PM

I just had a top end rebuild done everything was running fine but the car wouldn't start after it sat for 10-15 minutes when it was hot.

The fix for this was putting insulation around the turbo to prevent heat soak in the fuel system to keep the fuel from vaporizing in the lines. The car would always start right up after a nice ride on a flatbed.

Now the cars afr wanders while cruising it will have a small hiccups no major backfires or hesitation but this has happened before to the point where the car was almost not drivable. sounded like a gun fight coming from the exhaust.

The afr will bounce from 13.9-15.4 every few seconds when cruising between 2200-3200rpm. While acceleration on full boost it will drop to 10 and creep up to 12.4.

after coming off full boost cruising afr will be 13-13.5 for about 30 seconds and then go back to bouncing around between 13.9-15.4

I noticed the ground wire coming from the permatune box 6pin connector was loose not making proper contact popped it out connected it properly. I'm not sure if this could have been the cause for the major backfires I was getting before while cruising.

The WUR has been tested twice and is operating properly.

Any input on what could be causing this would be helpful.

Mods on the car are
K27 hi flow
fabspeedIC
cams sport grind from elgin cams
zork tube
rarlyl8 heads to be installed early april

k930 · 03-19-2022, 04:04 PM

02 sensor was just replaced
fuel accumulator was replaced
ignition coil is also new

reclino · reclino's Garage

Possible bad connection at O2 sensor?

k930 · 03-19-2022, 06:24 PM

I'm going to check 02 tommorow. hopefully weather is better tommorow so i can get a good drive in. It was 38f and pouring rain today when I went for my first drive of the year

Noah930 · Noah930's Garage

Quote:

Originally Posted by reclino

Possible bad connection at O2 sensor?

Funny, but that was my first thought, as well. Because of the long rubber shroud on the female end, that O2 sensor connector can look connected but not be. (We have a visual check for bienniel smog here in CA. Need to make sure that everything at least looks like it's intact and working, even if it's not.

)

mark houghton · 03-20-2022, 04:40 AM

Quote:

Originally Posted by k930

I noticed the ground wire coming from the permatune box 6pin connector was loose not making proper contact popped it out connected it properly. I'm not sure if this could have been the cause for the major backfires I was getting before while cruising

Did that poor ground solve your problem? Your misfires, if ignition related, will cause your AFR's to bounce around as the result of intermittent fuel combustion.

Ken911 · 03-20-2022, 07:42 AM

i had a similar problem i chased for several years it turned out to be the green wire from the distributor. It was cooked right where it connected to the plug on the distributor.

pkabush · 03-20-2022, 07:46 AM

Quote:

Originally Posted by Ken911

i had a similar problem i chased for several years it turned out to be the green wire from the distributor. It was cooked right where it connected to the plug on the distributor.

Same thing happened to me. The dreaded green wire.

Ken911 · 03-20-2022, 08:45 AM

yeah it took forever to find it because it was intermittent. until it finally failed completely. the whole wire looked fine when i was troubleshooting it was only the end that was cooked and you couldn't tell unless you unplugged it and looked.

k930 · 03-20-2022, 05:18 PM

I'm pretty sure the ground solved the misfire/backfire problem drove 200km since I connected the ground properly and no misfires or backfires. However the afr is still wandering maybe look into this green wire?

k930 · 03-20-2022, 05:22 PM

anyone have any info or wiring diagram of the green wire?

k930 · 03-21-2022, 03:44 PM

I unplugged the 02 sensor car is running properly no wandering afr. 13.7-14 at cruising speeds and does not bounce around at all stays at 13.8 most the time. I must have fouled up the new sensor when the car was running poorly. Is there any major downside to running this rich without 02 connected?

Alan L · Alan L's Garage

Quote:

Originally Posted by k930

anyone have any info or wiring diagram of the green wire?

The green wire goes direct from the dizzy to the Electronic Ignition unit terminals 7/31d.
According to my wiring diagram there is a two pin connector part way along. I don't recall seeing this.
Alan

gsxrken · gsxrken's Garage

13.8 is only a tad rich if you’re running E10 gasoline. That’s fine. If you had an adjustable WUR you could tweak it up but probably not worth the $500 for just this if you like your fueling everywhere else.
The green wire is good preventative maintenance. Pelican sells it but as a pig tail and as Alan noted, not all cars have the connector to use it. My car’s green wire ran straight from the distributor to the CDI box; no connector. Timmy2 on this forum can set you up with the proper length of green wire and a connector to splice in so you can then use the pigtail that goes into the distributor.

Matt at Pelican Parts · 03-22-2022, 01:56 PM

I show this green wire in 2 different versions on pelican's site.

Bosch 1-234-431-290 (128mm) (Bosch)
or
928-602-907-00 (700mm) (OEM)

You might want to double-check fitment but both appear to be available