Hesitation at WOT; Backfiring, TFI Module? Tried everything!!

ozanracing · May 2, 2007

*UPDATE*
I tested the coil's primary/secondary resistance and they were right on spec.
So the coil is ruled out.

The MAF is backordered, I called today and they said Next week, but upgraded to overnight shipping.

I'm going to test the TPS right now, then it's down to the FPR, (I have a feeling it's the culprit now)

I'll update soon........

Aliate X · May 2, 2007

ozanracing said:
Damnit.

After doing more research, I've definitivly ruled out the maf from WOT misfire/backfire/hesitation
etc. The EEC IV reverts back to pre-programmed spark and fuel tables and ignores the MAF
at full throttle. On later 94-95 cars with EEC- V the MAF IS refrenced at WOT....So>>> I'm now thinking
ignition crossfire? (spark plug cables could be damnaged and now have too much resistance??
But for this to just *BAM!* happen one day when I turn the car on makes me think....it's
not the wires....I'm going to check
the primary/secondary restince on the coil and see if they are withen spec....Maybe the coil went bad???

Okay, so rewind back to 2 weeks ago....Car was driving proper....One day the motor just shut off
(see this thread...) anyway a connector had come undone on the fuel pump in the tank.
I fixed it and everything was fine...For about a week. (could this be related?) SO then I was trying to get the idle
speed/quality fine tuned. I decided to unplug the ISC motor and set the idle to 900rpm.
Then I unhooked the battery and let the car sit overnight. In the morning I started it
up and forgot to plug in the ISC connector. I drove it for a block or 2 and noticed the idle
was hanging up at 2500rpm. I remembered the connector and plugged it back in with the engine
still running. EVER since then the performance has deterioited to the point where I dont
want to start it untill I get the new MAF to try. But what the **&^% I don't think this is going to fix
the car.

SO>> What now? How can I test the magnetic pickup in the dizzy? If the maf dosn't fix it, and the
magnetic pickup/coil/new wires also dosn't fix it....Fuel? I don't have a FP gauge in the cowel, only
mounted on the fuel rail. So I cant tell if there's a pressure drop/spike going on at WOT....hmmmmm....

Anything else? Should I do a compression test? I dont have the adapter for my gauge, but it's prob. cheap...
Let me know if any other ideas come up....

I dont know where you read that but that is not true. My car was sputtering like hell when I would floor it but ran fine just driving around normally. It went 16.7-16.9@88mph consistantly, opened up the MAF to find that the small wires on the posts were COVERED in grease/dirt, cleaned them off went back to the track with NO other changes went 14.4@95.

795.0pacecar · May 2, 2007

I'm thinking fuel starvation.

89fiveohman · May 2, 2007

hey man look into re adjusting the throttle position sensor. after adjusting the screw on the throttle it moves the sensor inside of it. it needs to be set right at .990-1.0 just a suggestion good luck

2002BLGT · May 4, 2007

I would bet money its the pickup in the distributor

getusummm · May 5, 2007

Why dont you just check the damn codes???????? Or do you just like throwing money at it?

ozanracing · May 5, 2007

It was the TFI module all along.
I tested/set the tps, pulled the FPR and checked it for leaks/ruptured diaphram,
Re set the timing....And as I turned the dist to advance the timing, the car died.
Repaet, same thing. So I got to looking at the tfi connector, and the pins were loose/getting a bad connection. Fixed that, set the fuel pressure back to 36.5psi, timing to 16*, and the WOT problem is gone.!!!!!
Now when my MAF gets here that is still backordered from JD's performance (kinda BS customer service) I'll try it out and see if it makes the driveability better.

Thanks everyone for your input and helping get this thing diagnosed.

2002BLGT · May 6, 2007

getusummm said:
Why dont you just check the damn codes???????? Or do you just like throwing money at it?

bad pickup wont throw a code

bandmc · Jun 8, 2007

Actually, the MAF does come into play at WOT. Had a problem where I fell dead on my face at WOT, clocked the MAF, problem gone. Didn't have any backfiring issues or anything else though.

Hesitation at WOT; Backfiring, TFI Module? Tried everything!!

ozanracing

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