gt40 motor and mark VII ecu problems

[89LincolnTWNcar]

Hey everyone, its been a while! I am still driving Anabelle most every day. She really needs some tuning, I am running the stock 1991 Mark VII ecu speed density with GT40 heads, GT40 intakes, 65mm TB, lightning egr, and the ho cam retarded 4*. She will backfire if I get on it real quick sometimes and after starting up will rev then bog and almost cut off if I don't pump the gas. Seems to be running very rich. Will a mass air conversion clear this up, or do I need chipping/tuning at a mustang shop? trying to decide the best route to take. Thanks ya'll.

[Grand Marquis GT]

Gee, this sounds like the same problem i'm having, minus the running rich part!!

[gadget73]

Is your TPS good? Sounds sort of like wonky tps symptoms. Also, are there any leaks on the vacuum line to the map sensor? MAP has proper vacuum? When I did my Explorer intake I found that a dirt dauber had built a nest in the pipe my MAP connected to, so I was getting no vacuum. car ran all kinds of f'd up.

[89LincolnTWNcar]

the TPS is off an explorer I think, could that be a problem?

[gadget73]

Are the plugs even the same on those? I could have sworn they had different connectors. If it plugs in, its probably compatible tho. Easy enough to check, just backprobe the connector at the green wire and see if you get ~1v at closed throttle, and ~5v at WOT (engine not running of course).

Have you checked the vacuum on the motor? If its low, it will run rich.

[mrltd]

I can't rememeber which TPS I used....

[89LincolnTWNcar]

I think my rich running is due to my 160* thermostat. Also my TPS reads 1.30-1.60 volts when closed as discovered by 88grandmarq. He tried hogging out the screw holes to make it adjustable, but it wouldn't get below 1.30.

[Pirate]

I think my rich running is due to my 160* thermostat. Also my TPS reads 1.30-1.60 volts when closed as discovered by 88grandmarq. He tried hogging out the screw holes to make it adjustable, but it wouldn't get below 1.30.

Have you screwed around with the idle-speed screw on the throttle body?

One other note: I'm a little concerned that the speed-density MK7 ECM may not be the best match for these cars....is anyone other than this poor schmoe or Tom having issues?

[Grand Marquis GT]

Have you screwed around with the idle-speed screw on the throttle body?

One other note: I'm a little concerned that the speed-density MK7 ECM may not be the best match for these cars....is anyone other than this poor schmoe or Tom having issues?

Actually my car had a LOT more ass off the line with the Mark 7 computer. It has a more agressive timing curve than the stang does, for the heavy cars.

[Lincolnmania]

both my mk7 ecm equipped ho cars kick ass........but both of them also have stock ho upper intakes.

[88grandmarq]

I think my rich running is due to my 160* thermostat. Also my TPS reads 1.30-1.60 volts when closed as discovered by 88grandmarq. He tried hogging out the screw holes to make it adjustable, but it wouldn't get below 1.30.

there are some tuning issues that need to be worked on.
We did some basics, but didnt have time to get indepth.
the ignition timing was not set correctly. the fuel filter looked like it was fairly old and had rusty, brown fuel coming out when we changed it.

the stock TPS sensor doesn't fit on the explorer throttle body correctly.

Getting the proper temp T/stat installed and finding a TPS that fits correctly and can be adjusted so the voltage is below 1v at idle, will help drivability greatly.

[89LincolnTWNcar]

I gotta hit the boneyard again and grab a bunch of stuff for the big brakes.

[gadget73]

I'm using a stock TPS on my Explorer intake and throttle body. No fitment issues. Not 100% sure what the TPS even came from, it was pulled from the box of random used EFI parts after the 1986 replacement part broke. Not totally sure what year my throttle body is either, it was a used eBay piece. It does have the tube on top for the crankcase breather if that says anything.

ECM works OK, but it goes lean pretty badly. It doesn't backfire, it just starts to run out of steam over 4 grand. I think my particular issue is just I'm moving more air than the stock SD tune is expecting. Tuning it to fatten the fuel curve, or just getting off my ass to install the mass air stuff ought to fix it (I hope). Its either that, or the head work is done in such a way that its just screwed up and beyond reasonable ability to fix.

[89LincolnTWNcar]

The only thing I can complain about on my car is that when I first start it up, the rpms fly up to 2000 then down to 200 and most of the time it cuts itself off, unless I blip the throttle. Then when I put it in drive it chokes itself out once in a while if its doing the surging thing. Sometimes it gets so bad I have to rev it to 4000rpm in Park before sticking it in drive, after the RPMS return to normal, but there is sometimes a cloud of smelly unburnt fuel when I do that.

[88grandmarq]

the car is still running rich, changing the thermostat will help.
replacing and adjusting the TPS should help even more.
while I was cleaning out my car, I found a spare TPS I had packed. it was burried under some other stuff and I forgot about it.

I wanted to check the ECM for codes, but since the Battery was disconnected and your test connector is broken it really wouldnt have done any good.
You may also have a faulty IAC motor, but you should correct the other tuning issues first.