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Old 04-15-2014, 05:35 AM   #1
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Unhappy Missing, hesitation, limp mode tranny, everything messing up

I have a 95 z28 with the auto tranny. Recently it has been developing severe symptoms. It started out when I tried to start it yesterday. It took a lot longer to start than it usually does, and it kept stalling unless I coaxes the throttle to keep the rpms high. Eventually I got it to idle, but idled really rough. I don't have a cam or any internal engine mods. Then later, I took it for a drive to see how it drove, and it would jerk from hesitating every few seconds, similar to the way it feels when you are about to run out of gas. At the same time,my speedometer went erratic and started reading crazy reading and skipping around, which then put my tranny into limp mode, and took out 4th and first gear. Between the car jerking and my tranny, I barely made it home.
I have checked fuel pressure, looks fine, reading between 42-50.
I recently replaced the spark plugs, fuel filter, and cleaned MAF sensor. I unplugged the MAF sensor to see if it would make any difference, and it didn't. I'm not sure where to go from here... I would appreciate any suggestions or help.. This is my daily driver and only car, so it's quite crippling at the moment. I can't scan for codes cause I don't have the right cable..
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Old 04-15-2014, 06:21 AM   #2
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Re: Missing, hesitation, limp mode tranny, everything messing up

Read this, and consider downloading the software and building or buying the correct cable:

http://www.camaroz28.com/forums/comp...95-lt1-874306/

Your fuel pressures are higher than normal, and exceed the GM specification, for 47psi max with the vacuum compensation line off the fuel pressure regulator. Did you measure the pressure with or without the vacuum line connected.

Is the SES light on?
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94 Formula A3+1: 381ci all-forged stroker - Callies Stealth, Oliver 5.85 billet rods, BME nitrous pistons / CNC LT4 heads / Comp Cams custom solid roller / TH400 + GearVendors OD / Strange 12-bolt - 4.11's / 300-shot N2O / Spohn suspension / 6-pt roll bar with integrated SFC's / AutoMeter instrumentation / MoTeC M48Pro engine management system / a few other odds 'n ends. 800HP/800LB-FT at the flywheel.
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Old 04-15-2014, 02:29 PM   #3
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Re: Missing, hesitation, limp mode tranny, everything messing up

I checked the pressure again, and my first quote is a little high actually, the pressure isn't quite that high, it's about 37-45 with the line disconnected. I have that program, and I'm planning on buying the cable as soon as I can. I didn't notice any lights coming on.
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Old 04-15-2014, 03:40 PM   #4
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Re: Missing, hesitation, limp mode tranny, everything messing up

Pressure at idle, vacuum line off should be a STEADY 43.5psi. GM accepts anything in the range of 41-47psi. The pressure should only drop below that value when you reconnect the vacuum line, and the regulator drops the pressure proportional to intake manifold vacuum, about an 8psi drop with a stock cam.

When the speedo went crazy, did you notice if the dash volt meter had dropped near the red area?

The PCM monitors the transmission, and will set codes for transmission faults, and those codes do not turn on the SES light. The fault code for the vehicle speed sensor (VSS) does not turn it on.
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94 Formula A3+1: 381ci all-forged stroker - Callies Stealth, Oliver 5.85 billet rods, BME nitrous pistons / CNC LT4 heads / Comp Cams custom solid roller / TH400 + GearVendors OD / Strange 12-bolt - 4.11's / 300-shot N2O / Spohn suspension / 6-pt roll bar with integrated SFC's / AutoMeter instrumentation / MoTeC M48Pro engine management system / a few other odds 'n ends. 800HP/800LB-FT at the flywheel.
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Old 04-15-2014, 03:59 PM   #5
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Re: Missing, hesitation, limp mode tranny, everything messing up

Well, for one thing, I'm not sure if my ses light even works, cause it's always off, even when you first turn the key,. I unfortunately did not notice the voltmeter on the dash,. I'm pretty sure my fuel pressure is good, it seems to be at least.
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