Odd backfire/miss

At idle I'm getting an odd miss and on decel w/ the clutch in, I get slight backfiring. Base timing is dead on, ignition @ 12*. Base idle was set to 725 RPM and the TPS was set to .93.. When I searched, these are the only culprits that I came up with.. and all of mine are within spec it seems. Can the TPS do this? Because I have a digital multimeter so I can't check for flat spots.

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Ryan Harris

88 TC, 5 spd, B&M Ripper Shifter, Walbro 190 LPH, Kirban, K&N, 3.73 rear, KS disconnected, BCS bypassed, 89K miles.

SPEC Stg. III, Perfection flywheel & rebuilt IHI going in!

Just pulled the codes, getting the awesome code 72 [Image: biggrin.gif] [Image: confused.gif]

My startup was noticeably crappy. The RPM lugged at around 800-950 for maybe 45 seconds, then it idled at 1200. I am officially confused.

Just swapped in my spare VAM, cleaned out the IAC & replaced the gasket, and reset the base idle and TPS again. The car runs EXACTLY the same???

Also, I noticed that with the IAC unplugged w/ the car idling @ 1000 RPM, it runs very smooth and doesn't skip or sputter! Can the IAC be the culprit?

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Ryan Harris

88 TC, 5 spd, B&M Ripper Shifter, Walbro 190 LPH, Kirban, K&N, 3.73 rear, KS disconnected, BCS bypassed, 89K miles.

SPEC Stg. III, Perfection flywheel & rebuilt IHI going in!

Put about 100 miles on the car. Startup is really bad, sometimes it stalls out and I have to start it back up again. I turn the key, and it spits and sputters and hangs/misses around 800 RPM, then dies. I start it again and it idles up to 1000 with that weird miss. I think it may be my IAC, I'm gonna try a new one today.

Let us know how the new IAC does.

think about doing a compression test? sounds like my car when it blew my HG

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1966 mustang
1988 tbird
Finally have mods that I can post... 373 gears with a brand new t5. K&N cone. Gillis set to 15 psi. Walbro 255 lph. Kirban afpr. Kelly Evo Z tires. Energy suspension front swaybar bushings. Rebuilt topend with stock components.

Working on a FMIC w/ the stock IC.

Code 72 or 78 indicates that while key power was present, VPWR had an interrupt, or interference from electrical noises caused the processor to reset, resulting in possible stalls, high idle rpm, lack of power on acceleration or other drive symptoms.

http://www.tbirdheritage.com/pinpointtes...stepid=QE1

Hm. My alternator has been making some electrical noise for a while now... Interesting. Thanks JT, I'll have to hit up the JY for a 3G soon.

Brian, I don't think the HG went.. no chocolate milk and the driveability is great. Car runs very very cold still even in town, perhaps TOO cold on the highway. I can only imagine what it's gonna be like this winter with the damn thing never heating up! [Image: redface.gif]

The miss is a small one, and the backfiring doesn't seem to present a problem other than sounding like crap. And my compression tester broke [Image: frown.gif] lol

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Ryan Harris

88 TC, 5 spd, B&M Ripper Shifter, Walbro 190 LPH, Kirban, K&N, 3.73 rear, KS disconnected, BCS bypassed, 89K miles.

SPEC Stg. III, Perfection flywheel & rebuilt IHI going in!

[This message has been edited by Ryan H (edited 09-25-2005).]

non of my fluids mixed and it still drove.

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1966 mustang
1988 tbird
Finally have mods that I can post... 373 gears with a brand new t5. K&N cone. Gillis set to 15 psi. Walbro 255 lph. Kirban afpr. Kelly Evo Z tires. Energy suspension front swaybar bushings. Rebuilt topend with stock components.

Working on a FMIC w/ the stock IC.

Car kept stalling earlier, got codes 23 for KOEO and 14 and 42 in CM. I reset the TPS and it wouldn't drop below 1.08v, so I said screw it. I'll be replacing the TPS, IAC, and plug wires all at once tomorrow. Hopefully this crap will end some day [Image: mad.gif]