Suggestions or Ideas welcome!!

[MdMustangs]

Ok I usually work through most issues on my own but i am gonna throw this one out there and see what happens. I usually consider myself pretty good with foxbodies but this is a little puzzling.
I have a 86 GT. When I pulled the motor a few years ago to do an extreme engine and engine bay makeover I made a few mods. I would like to point out that after buying the car, I went right into pulling the motor so I cannot say if the problem was there before hand.
I pulled the motor to clean, paint, re-gasket, etc... while apart I installed a Crane model 2020 cam (designed for speed density cars) and a explorer upper and lower. I deleted ALL emissions equipment during this time including the EGR. I am running a stock 86 Mustang throttle body on the explorer intake. All vacuum lines were replaced but also allot deleted if it was emissions related. It has stock heads, ignition, offroad H pipe, etc. I did a Mass Air conversion before startup as well. After startup, the car would start great but after idling for a short time it would go into this really bad sorta limp mode where it was loading up, running rich and just over all idling like crap. Well after fighting it to no reward i decided to go to speed density. Well it got better but it didn't fix it. I had to end up running the car with the butterfly on the throttle body cranked way open with TPS voltage reset to about 1.0 volt. It seemed to still have the same proper start to then begin to act up after idling for a short time. The only some what fix seems to be having the butterfly way open on startup. IAC has been replaced, TPS is good and MAP sensor has been checked. The one thing I never did during all of this was replace the O2 sensors. I desided to swap the O2's for a new set recently but it acted the same ( I did NOT pull the battery cable and reset the EEC). I checked at the O2 plug, I have a good ground and the 12 volt positive with key on. Haven't checked EEC voltage at the O2's yet. I am wondering if I need to make and install a EGR Fake plug? I can't see why no EGR would be doing this but who knows. I am sure it has a code or two from stuff that was deleted. Maybe I need to see how it acts with new O2's after pulling the battery cable for awhile to rest the EEC. Anyone got any ideas???

[83gtstang]

Try to ping JACook on here, he is impressive with injection problems.

[83gtstang]

I'm curious, are you running catalytic converters?

[Ethyl Cat]

Sounds like it is getting bad info once going to closed loop operation. You need to continue your check on the Oxygen sensors.

How do you know it is going rich?

[MdMustangs]

I'm curious, are you running catalytic converters?

No I am not running converters. Offroad H Pipe

Sounds like it is getting bad info once going to closed loop operation. You need to continue your check on the Oxygen sensors.

I agree with you! I am not 100% sure its going rich but. When it was setup mass air I really think it was. Fumes were awful. The are pretty bad now but being the fact that it only acts somewhat right is when I open the flapper on the TB, Seems more air helps. I am going to check the O2 SIG voltage soon. Didn't get to it yet.

I also want to point out that I am no stranger to wiring and controls. Been fooling with Foxbodies for along time. I have also been a control tech for the local power co for over 25 years.

Here is my car too





How do you know it is going rich?

[Ethyl Cat]

Bad fumes are more akin to lean misfire than rich running. When they happen, the engine is pumping raw fuel out the tailpipe.

Nice ride!

[84.5crgt]

What kinda fuel pressure do you have? If ecu thinks it's running lean due to low fuel pressure it could be trying to fix it by holding the injectors open to long to counteract and dumping to much fuel.

[83gtstang]

Reason I asked about the cats is sometimes off-road hpipe will not allow the heat needed for o sensors to read correctly/back pressure. Could be sending false signals to ECU. Anybody else hear of this issue? My old boss had an 86 with the off-road h pipes and it gave him similar issues, he ended giving me his old motorsport stainless hpipe once he recognized the issue.

[MdMustangs]

What kinda fuel pressure do you have? If ecu thinks it's running lean due to low fuel pressure it could be trying to fix it by holding the injectors open to long to counteract and dumping to much fuel.

Its been a little while since I checked it but I do recall it being good. I was on that hunt back over the summer. I put a new vacuum regulator on it just to be sure.

Reason I asked about the cats is sometimes off-road hpipe will not allow the heat needed for o sensors to read correctly/back pressure. Could be sending false signals to ECU. Anybody else hear of this issue? My old boss had an 86 with the off-road h pipes and it gave him similar issues, he ended giving me his old motorsport stainless hpipe once he recognized the issue.

I didn't consider the cats being a problem but i have been wondering if the fact that I put a 165 deg T stat in it back when i had it apart, was that causing an issue? I wasn't concerned with having good heat because it sits in the garage most of the time. Do ya think it need a 190 deg?

Also I tapped the upper plenum for the ACT sensor on the explorer intake instead of the lower like the stock. Really don't think this is an issue. I have seen those ran in the intake air tube.

Between working late and it just so cold here in Maryland, I haven't felt like going out into the garage to work on it. I have a new MAP sensor to put on it. I also have a DA1 ECU to put in it out of an 88 GT.

I also have a a explorer throttle body I can put on it not that I really think that is gonna do much different than the stock 86 TB that is on it now.

[83gtstang]

Could be an issue, read this on thermostats

https://books.google.com/books?id=5p...ed=0CCMQ6AEwAg

[MdMustangs]

Could be an issue, read this on thermostats

https://books.google.com/books?id=5p...ed=0CCMQ6AEwAg

Thats interesting. I think something else I will change just to rule out an issue.