See anything on this list that might help you figure out this problem?

[SMEGMA STENCH]

Hi all. I have a 1987 Chevy Silverado 5.7L auto, 2WD. I know this is a mustang site and all, but I also know that its got some of the most knowledgeable people around. I finally got time to run to codes on my engine, and try to figure out why its sort of cutting out at certain RPM's, and why it just dies randomly when I'm driving. It can be restarted, but it takes longer then it should to start. But it pretty much always takes longer than it should to start. You have to crank on it for about... I'd guess about 2.5 seconds to get it to start. Unless you've already tried to start it and didn't hold down the switchkey long enough. Then it fails to start, but when you try again, it starts up like its supposed to. Fast. Anyway, here is the data from my scanner. This is live data from when I had the truck running at idle, in park, at normal operating temperature. So some of the data would fluctuate slightly as little things changed here and there. As for trouble codes... there weren't any. :-\

PROM ID: 9821

BATTERY VOLTAGE LOW: NO

RICH/LEAN FLAG: LEAN

LOOP STATUS: OPEN

ENGINE RPM: 775

THROTTLE SENSOR: 0.86 VOLTS

INTEGRATOR: 128 (I don't know what this is supposed to be or mean)

O2 sensor: It fluctuated between 134-145 volts when the truck was warming up. Once it got warm went back and forth from 114-123 volts

AIR DIVERT SOLENOID: ON

KNOCK SENSOR: 0 (I don't really know what it means by "0". Is that supposed to be zero voltage? Or maybe it means that the truck is not equipped with a knock sensor?)

BLOCK LEARN: 126 (Never heard of whatever this is)

02 CROSS COUNTS: 122 (Not sure what this means either)


I left out some random stuff that was listed by the code reader, just cause it was irrelevant or I already knew what it was and that it didn't have any effect on the problem. Such as the coolant temp, which was 183 degrees. And that the vehicle was in the Park gear, and was going 0 miles per hour. Just stuff we don't need. Everything else that the code reader gave is listed. Hope this info can help determine what the problem is.

[DC COBRA]

Kind of sounds like a fuel pump going bad, although those year models had a problem with the fuel filters. The intergator is a little high and the o2 is showing lean by not switching. I have seen the egr valve cause this similar situation, just some things to check.
Good Luck
DON

[SMEGMA STENCH]

Kind of sounds like a fuel pump going bad, although those year models had a problem with the fuel filters. The intergator is a little high and the o2 is showing lean by not switching. I have seen the egr valve cause this similar situation, just some things to check.
Good Luck
DON

Ok what exactly is the integrator? Its something new to me unless it also goes by a different name. Also, what do you mean by the O2 sensor "not switching"?

[Mark04]

Hi all. I have a 1987 Chevy.......... .

The problem is before the list.

[Your Name Here]

The problem is before the list.

FAG Build Ford tough with Chevy Stuff

[Mark04]

FAG Build Ford tough with Chevy Stuff

Buy a Chevy and you buy the best. Drive the first mile and walk the rest.

[Damnittsteve]

loose nut behind the wheel obviously

[SMEGMA STENCH]

Buy a Chevy and you buy the best. Drive the first mile and walk the rest.

ROFL! I guess I kind of expected to hear this stuff here.

loose nut behind the wheel obviously

Damn it steve, shut the hell up. I bet you hear that a lot don't you?

[DC COBRA]

Ok what exactly is the integrator? Its something new to me unless it also goes by a different name. Also, what do you mean by the O2 sensor "not switching"?

Intergrator is somewhat of measurement the computer uses to feed or take away fuel to correct the fuel mixture to a perfect say 14.7 to1 ratio. If intergator number is higher than block learn that means it is adding fuel to correct leanness or something like that. O2's need to switch from high to lower numbers so the computer can trim injector pulse to keep motor running efficient. It uses this info and other to determine injector pulse width, the amount of fuel needed is in relation to the numbers of intergrator and block learn table. This shit is sort of complicated but if you can somewhat figure what is going on its not bad. Then of course the newer the cars the more info and sensors and more headaches trying to figure out. You having an earlier vehicle actually isn't to bad to work on, but I think you have a leaning condition going on somewhere.

DON

[SMEGMA STENCH]

Thanks man. Naw I see what you're saying, it really doesn't sound all that complicated. But its odd that there is a lean condition and its not throwing any engine codes. I replaced the oxygen sensor when I got the truck a couple of years ago, and since then I've maybe put 10K miles on the truck at most. Then again, I've been wondering about sensor quality lately. I just went down to autozone and bought the bosh that they had for the truck. It wasn't all that expensive, and its not GM brand. And, it looks different than the ones that GM sells.

The more expensive AC Delco one is about double the price of the one that I have on there. I'm wondering if its just low quality crappy sensor that is causing my problem.

[DC COBRA]

An o2 sensor can goof up and not read right and cause the computer to lean out the motor to kill it. all you can do is replace then check the readings, if it is switching your good to go, if not you still have the problem. Although if it not throwing codes I would suspect the fuel pump as this would be a driveability issue and not something the computer can really pick up on. Go over it pretty good and cover all your bases, make sure no vacumn leaks, unhook the egr valve to make sure it isn't opening off key, make sure vacumn source at map sensor, make sure throttle body gasket is not blown. One test you can do is check the small return line at the back of the throttle body, while vehicle is running loosen the line and there should be some gas leaking out of it, if not you do not have enough fuel pressure, that points to a bad pump or regulator. Nineteen years of being in business never have replaced a regulator but replaced a many of pumps. Today's fuel with ethanol additive is taking a terrible toll on pumps here lately.

DON

[SMEGMA STENCH]

Ok well I just remembered something that I should have thought of a long time ago. It's pretty unlikely that its the fuel pump because on the driver side tank, I just had the fuel pump replaced a year ago. On the passenger side tank, the fuel pump is the same one that came with the truck when I bought it. But no matter what tank I use, I still have the same problem. So I find it to be unlikely that its the fuel pumps.

I'll check everything else you said though, the EGR valve looks pretty old and crusty.