Searched, Read, Tried EveryThing.........Car Still Runs Rich!!

[Alex in Houston]

Posted this on a few national boards but I haven't recieved anything of substance or that I haven't already tried/replaced and ruled out. Don't know if anyone reads this section but I figured it couldn't hurt to post it just in case (as there are a few knowledgeable guys on here)


As the title states my car runs rich. At idle, give it gas and black smoke shoots out the back. Tail Pipes and lower back bumper cover are black/sooty after a short drive, hell just let it sit at idle and give it gas, they'll become sooty.

302 (stock forged piston rebuilt a few years back. Less then 1500 miles since rebuild)
TFS stage 1 cam instlled "Straight Up"
AFR 165 with 64cc chambers (New Springs and Manley Valves installed a few years back. Less then 700 miles on them since then)
1.6 Stud Mounted rockers
GT40 Upper/Lower (lower port matched to heads)
MAC 1 3/4" Long Tubes, Custom Catco 3" H-Pipe that feeds into 2.5" Mac Flowtubes/Mufflers/TailPipes
Kirban Adjustable (set at 37 Vac disconnected. Have changed back and forth between stock and Kirban, no change in results)
19# Injectors (have tried several sets, same results. I have the 4 hole version in the car now. Heard the pintle type clog more often. )
AutoLite 3924's gapped at 42
Brand New Set of Bosch 8mm Wires
Stock 70mm Mass Air
A9L computer (Complete Fox Body Harness and Distributor) Timing at 18 (set/checked with SPOUT out)

Car pulls 12-14" of Mercury pretty steadily (TFS cam) and idles rock solid at 900 (3.5" tach on Dash). Drives fine outside of the fact that it has no balls! The car was turbocharged for years prior to this. I grew tird of the maintenance and crowded engine bay with the twins (hence the low miles over the years. Always on jackstands or sitting while I saved to fund something else turbo related.............What a waste of time/money over the years) and sold all turbo related items.

Last time the car was N/A it had TFS TW with an E-cam. This was back in 98 and it ran 12.9 @ 108 on street tires (car is a 95 GT). Had constant issues with the Valve Guides (TrickFlow fixed them 3 times. The second time they converted them from pedestal to stud mount. The Third time they changed the valve guides and I sold them once I got them back. Have no idea if they held up) Bought the AFRs about the same time I got into TurboCharging the thing (hindsight, wish I would of left it N/A. Drove it waaaaayyyy more then I worked on it, LOL)

Anyhow, I know it should be easily as fast as my 06 GTO (my GTO is stock down to the paper filter..............for about 20K more miles :evil1: ) Unfortunately it's not (not even close). I'm sure the issue has to do with the richness but I'm at a loss.
Check Engine light has never come on BUT I ran codes and get 34 (EGR above limit, guess it's not opening) and a 67 (neutral switch in tranny to EEC) Both of those will basically only have an effect on idle and I think the EGR will cancel decel fuel shutoff. Though I get no popping out the exhaust during decel.

I'm going to remove the TFI and have it checked. I do remember a time back in 96-97 when the TFI went bad only on the advance. Had a very helpful/knowledgeable guy at an Autozone run the test. First time I heard of such a thing but a new TFI (bought a Motorcraft, hate AutoZone electrical items, lol ) fixed the problem.

Outside of that, I'm out of ideas and thus the need for this long arse diatribe

When me and my Dad marinated on it for a while. We came to the conclusion that this has been an issue for a while. Figured it was just masked by other things. Now that it's pretty much just a basic H/C/I car, it's a lone soldier/problem.

Any and all help is appreciated.

[Otis!]

Marc,

Have you had the fuel tank out? Could it be you pinched the return line?

[Blue91]

Yeah, what's the FP set at? Have you checked out the BAP sensor? I would think if that was faulty the eec would do funny things that it shouldn't be doing.

[Alex in Houston]

Nay, the tank was out years ago (put in a 255lph) but I doubt the lines are pinched. I have a guage on the rails (schrader valve) and an electric one on the pillar. Both read 37 ps1 (vac line off) and never goes over that while driving. Wouldn't pressure be pretty high is the return line were pinched?

Fred, I haven't tried swapping the BAP (crossed my mind a couple of weeks back but disregarded it as the computer never threw a code for it). But at this point, I can't see how trying a different one would hurt. I don't have one handy right now but will get one tomorrow and see if that helps. If it does, as stupid as I'll feel (wouldn't be the first time) I'd be ecstatic, since I'm pretty tired of messing with it at this point in my life.

Thanx for the suggections fellas, I'll report back tomorrow with results.

[Thoroughbred]

update?

what about some abunch of dirty old 19lb injectors? O2's? Something on the MAF element?

[Alex in Houston]

Tried several sets of injectors, no way 3 sets are all bad. The 02's are new and switching just fine at idle and part throttle. Go WOT and they read full rich and no longer switch.
I didn't get out to get a BAP sensor. I worked on the fan (low speed was not coming on................after trying everything and about to bypass the CCRM. Discovered the wire had come loose at the splice. Soldered it and heat shrunk it, good as new now). Put in a Crane Hi-6 and spent the rest of my time working on the CarPuter for the GTO. I'll allot some time during the week and get the BAP swapped as well as R/R the TFI. I had to do so much to return it back to N/A over the past few weeks, that I've just resigned to taking on one task at a time. Just so many little things that needed attention. Steadily getting them done but this rich conditon issue was not one I had forseen.

[Alex in Houston]

Decided to run a compression test as a way to rule some things out. Motor warm, all plugs out (with burns on my hands to prove it) and throttle wide open :

1---155
2---151
3---165
4---135 (squirt of oil = 155 ---ring not sealing well)
5---155
6---160
7---150
8---150

Plugs from Drive side had the most soot on them for some reason. Seems strange since cylinders 5-8 have the highest compression across the board. It's also the same side for the tail pipe that smokes the heaviest.

Plugs laid out in order (1-4 then 5-8) from left to right

Plugs from drive side
http://pomoforacing.com/forums/attachment.php?attachmentid=2017&stc=1


Plugs from passenger side
http://pomoforacing.com/forums/attachment.php?attachmentid=2016&stc=1

Outside of 4 being a bit low on compression (and it's plug looked no worst then the rest. No oil on it or anything) I can't say the motor is the culprit of the richness.
Tried a New BAP, changed the TFI to a known working MotorCraft one and went over every ground in the car. Still can't pin point the problem. :rant:

[blk95gt]

Had a prob with my car running a rich at idle and kinda stumbling, come to find out it was the coolant temp sensor gone bad. I unplugged it and the car cleaned up...but with a check engine light on. When that went bad it was keeping engine in cold start mode...not letting computer go into normal operation. Just a suggestion.

[scottmrit]

have you taken the car to a dyno to see where you stand on power??