86 gt issues

redknight290 · Mar 19, 2008

I've posted a few times about different issues with my car but this is the one that left that is really becoming annoying to try to diag.

I start the vehicle, it runs pretty ****ty, will buck, surge, while idling and while driving, if i hit the gas hard it will refuse to go any higher than 3500 rpm, and sometimes the rpms will start fluttering a little before that. New Tfi module, Cap, rotor, coil, wires, I checked fuel pressure it sits at around 32 with the fpr vacuum line connected and right around 40 without it connected, and when you hit the gas the pressure stays consistently at 40. My car is basically stock so i know im not outflowing the injectors.

thanks for all help

BK_CAULEY · Mar 19, 2008

have you pulled the codes yet? you might wanna try that first and let us know.

http://www.troublecodes.net/Ford/

93 LX · Mar 19, 2008

check for a vacuum leak.. I had one under the intake on the PCV hose..

speedytang · Mar 20, 2008

Does the exhaust smell like gas?
Make sure you don't have a leaking vacuum hose to the MAP sensor on the firewall. MAP is what keeps the Speed Density cars going. If you search you can test the MAP with a vacuum pump and a Multimeter.

stang&2Birds · Mar 20, 2008

Buy a $35 code reader, or junk the car.
Sounds like the MAP sensor. Or, it could be a vacuum leak. MAP sensors go for ~$80, so you want to make sure that it's the MAP sensor.

redknight290 · Mar 21, 2008

ok so i pulled codes, and the map sensor was replaced maybe 3 weeks ago when it actually went bad.
codes
24-ACT out of range
81-thermactor air problem
21-ECT out of range or not sending right temperature

would a vacuum leak really cause problems when revving the engine, because isn't there no manifold vaccum then?

cenok is family · Mar 21, 2008

a few things to look at: some of your injectors could be bad. just cause you have proper pressure at the FPR, doesn't mean the squirters are working correctly. also, i see that you pulled the codes and your ACT and ECT sensors are bad. those are 2 highly important sensors your eec uses to help determine a/f and timing. both are cheap and easy to replace, so i'd start there since you know they're both bad. THEN move on to the map sensor.

NIKwoaC · Mar 21, 2008

redknight290 said:
ok so i pulled codes, and the map sensor was replaced maybe 3 weeks ago when it actually went bad.
codes
24-ACT out of range
81-thermactor air problem
21-ECT out of range or not sending right temperature

would a vacuum leak really cause problems when revving the engine, because isn't there no manifold vaccum then?

You are right, at WOT, there is virtually no vacuum, so for the falling-on-its-face problem during full throttle is likely not a vacuum line or MAP pressure sensor problem.

If your ACT and ECT are throwing codes, replace them. Also, check the wiring harness near these sensors, to make sure it has no shorts, worn down insulation, or disconnected wires. Does your car have a low-temp thermostat? Just wondering, seeing as how the ECT is "out of range or not sending right temperature". Not sure how much that would really affect it, but I've heard bad things about using a thermostat colder than 180 degrees.

cenok is family · Mar 21, 2008

NikwoaC said:
You are right, at WOT, there is virtually no vacuum, so for the falling-on-its-face problem during full throttle is likely not a vacuum line or MAP pressure sensor problem.

If your ACT and ECT are throwing codes, replace them. Also, check the wiring harness near these sensors, to make sure it has no shorts, worn down insulation, or disconnected wires. Does your car have a low-temp thermostat? Just wondering, seeing as how the ECT is "out of range or not sending right temperature". Not sure how much that would really affect it, but I've heard bad things about using a thermostat colder than 180 degrees.

well considering your car runs in open loop until it hits about 170*ish, yeah, id say your car won't run to it's full potential if you have a 160* t-stat. a cold t-stat won't cause the surging, bucking and such the OP is experiencing though.

redknight290 · Mar 21, 2008

the thermostat in my car is a motorcraft 192 degree. It runs at proper operating temperature. I was also thinking it could possibly be my distributor pickup i've heard that from a few people it will cause all sorts of problems when it starts to go bad.the vacuum lines to the map sensor are brand new. Timing is set at base 10 degrees.

I am going to replace the ECT and ACT and see what happens i just didn't picture them going bad to cause my car to be so messed up.

redknight290 · Mar 21, 2008

ECT and ACT replaced, problem still not solved

thinking of throwing a new dizzy in it. Whats the best way to verify if my injectors might be clogged or bad. Anyone have any thoughts at this point?

thanks a bunch for the help, we'll get it fixed soon enough.

Mustang5L5 · Mar 21, 2008

redknight290 said:
ok so i pulled codes, and the map sensor was replaced maybe 3 weeks ago when it actually went bad.
codes
24-ACT out of range
81-thermactor air problem
21-ECT out of range or not sending right temperature

would a vacuum leak really cause problems when revving the engine, because isn't there no manifold vaccum then?

Was the car cold when you ran the test?

The ECT code is common when the engine is stone cold. I suggest running it fully warmed up

86 gt issues

redknight290

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BK_CAULEY

it's built for speed not longevity, woman

93 LX

speedytang

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redknight290

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cenok is family

NIKwoaC

中國製造

cenok is family

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86 gt issues

New Member

it's built for speed not longevity, woman

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