Will start at beginning.
Wife driving to work on freeway, car looses power she gets off and takes back road home gets about half way and car will only get up to about 20 mph. End up having it towed.
Get it home start working on it, car won't stay lit. Check fuel pressure, pressured up good but fell like a rock, so replaced FPR. Car starts and idles fine, now for the good part. Car will idle all day long but as soon as I open throttle its like someone choked it. Dies immediately. Restart car, and if I open throttle slowly can get to about 1200 rpm, same thing car dies.
Things I have done so far are
1. tore apart vapor recovery system, line from purge valve to charcoal canister was completely packed with charcoal, clean out line seems ok now.
2. replaced EGR, while checking it with vacuum pump it would open but it would stick when releasing vacuum.
3. Have noticed vacuum is reading low, only about 16 as I open throttle vacuum drops. Checked vacuum in the past and was about 22.
4. Have some scan results on cold engine and hot engine but nothing with car running as i'm waiting on gaskets. Also having problem with scanner, have to jiggle connector to get it to read.
COLD HOT
Coolant temp 55.8 F 201.6
TPS 0.66 volts 0.66
O2 408 mVolts 408
Block Learn 128 128
Integrator 128.00 128.00
Air Idle Mtr pos 160 steps 160 steps
Desired Idle 3187 rpm 3187 rpm
MAP Sensor 4.60 volts 4.68 volts
Manifold Air Tem 55.7 F 163.4 F
Battery Volts 12.0 volts 12.0 volts
Learn Idle Pos 44.00 steps 46.00 steps
Oil Temp 47.7 F 173.30 F
Park/Neutral Detected Detected
Rich Lean Flag Lean Lean

Will get scan while running as soon as I get it back together. Got a feeling will run same as before with vacuum low and choking.

 

What year vette?

 

Are your injectors consistently ohmd and pulsing?

 

1991

 

Excuse me for being stupid but that just went over my head

 

You may have leaking injector(s). You should run a pressure test. Also, no pulse signal to injectors can mean a bad injector relay or PCM driver circuit.

 

Could it be a clogged cat?

 

I,ve got a 96'.....and when it did that, it was the fuel pump. It gave a code that was a fuel pump clue. Good luck

 

Just ohmed injectors, all 8 of them read 16.3 to 16.4. Not sure how to pressure test, not sure I would need to as it idles rock steady.

 

Not sure how to check quickly. Any ideas

 

Fuel pump pressures up to 42 stays at 39 while engine idling when I increase rpm's to 1200 just before it chokes, pressure stays steady.

 

Is the (dust) cap missing over the ALDL?

In that case a prev. owner might have been reading codes to once in a while.

Reason I mention this is, when you are a little careless with the ALDL connector, the small pins in it can retract (pushed back in the connector).

On my ´91 the cap is still there, but I had the same problem with a scanner, just to find out after a closer look that the top right pin (A) was pushed back quite a bit.

In such a case you can take a pair of small pliers on the back side, to hold a wire in place when you push in the scanner´s connector.

Temporary solution of course.

Might be a tip for those that have problems with their scanners mal- or not functioning.

 

Just checked ALDL connector. Has female receptacles. Held 3 wires used by scanner (EZ-SCAN 6000) to make sure they are connecting, still says "Vehicle not responding", if I jiggle it around a while it will connect but its a PIA.
Fed-Ex just showed up, so going out to replace all the plenum gaskets so I can fire it up and see if I can get a closed loop scan.

 

Yes, they are female, I´m here in Europe, so couldn´t come up with anything better than "pins".

I think we have the same scanner.

AutoXray, isn´t it?

Took a few turns (taking out the batteries, and start all over putting in the right info like GM, vin 8, year and so), don´t know what I did, but I got it working in the end.

Be sure you go by the book (scanner), so you connect the scanner to the ALDL in the right order, that can mess up things.

Are all the sensors still connected in the car/engine?

If you have the engine apart, and disconnected some connectors, it won´t work of course, guess you know that.

 

I'm thinking that your on to something here.

When the throttle is opened, vacuum will increase fuel pressure.
This increases fuel flow to assist acceleration. IF vacuum is reading low, the mixture leans rather than enrichens.

I'd start looking for a vacuum leak. Might try plugging some of the larger hoses for testing purposes.

Good luck

 

Thanks for the hint on removing batteries and starting over on scanner, seems to work fine now.

 

Cool, keep us posted on the progress.

 

um.. vacuum drops as the throttle blades open.

 

Pappy.72 just checked exhaust pressure per the book at the air pipe after removing the check valve. Think you nailed it pressure 7 p.s.i., revs like it should. Know of any way to gut the cats till I can replace. That way I can at least use the car. Also any ideas on CAT system, I'm in California so got to have. Only need front half as I have a BORLA system in back.

 

Actually you got it backwards. When vacuum drops, the press rises app 5 PSI. Watch what happens when you remove the vacuum line to the FPR. That small press change will not cause what the OP describes.