Strange erratic problem with 350 TBI engine.

[82355]

A little back ground on the vehicle first. I have a 1988 V10 Suburban. The engine in it consists of a 1990 IROC-Z 350 short block (with forged flat tops), a 1995 Z28 LT1 cam, Vortec heads (the lesser casting), 1.5 roller rockers, GMPP TBI Vortec intake, headers and 2.5" dual exhaust, no cats, no smog pump, no EGR. It has been together like this for a while and ran fine. Before this setup it had ported throttle body swirl port heads and a stock intake, but with an LT4 Hot Cam. It ran fine with that combination as well, the power band was just to small (cam came into power, heads ran out of steam).

Well a few months ago it started having a random cut out. Was no big deal, just annoying. Then it got progressively worse. I finally broke down and installed new plugs and wires, and installed a couple header plug boots. I had found a couple burnt plug wires, and figured that was my whole problem. It actually ran much better after this, so that was some of my problem. Then is started happening again.

It has gotten progressively worse. It has something to do with the how long the engine runs as well. I live three miles from the highway, so if I jump in and drive it to the highway, it runs fine for three miles, then I stop at the stop sign and try to take off. I have to go up a decent hill there, and I've noticed a load will trigger it. So when I go up that hill it starts bucking from the engine cutting out.

Also if I leave it sit and warm up for a little bit, it will do the same thing, but right away.

The odd part is that I found if I merely shut the engine off and turn it right back off, the problem usually goes away.

Suggestions? Questions?

Where do I get the cable to hook up to a laptop? What kind of laptop do I need?

Martin

 

[y5mgisi]

My bet is either fuel pump is crapping out/has a bad ground or the ignition module in the dist is crapping out.

 

[82355]

Why does turning off the engine make it go away then?

Martin

 

[dyeager535]

Cable: http://www.gearhead-efi.com/Fuel-In...e-Forum-Buy-ALDL-Cables!&highlight=aldl+cable

I can't help on the type of computer required, but I *think* tunerpro RT http://www.tunerpro.net/ is usable with just about any version of Windows, not sure on the Mac side. I know I've used it with Windows 2000 and XP.

I'd be looking at fuel pressure and injectors myself. Ignition of course could be an issue as well, but fuel pressure and injector testing/observations are easier to take care of than trying to diagnose an "intermittent" potential ignition problem IMO.

 

[y5mgisi]

Fresh jolt to tye fuel pump/ letting the module "reset"? I dunno. I would just check tye fuel pressure while its being funky, and pocket a ign module from the junk yard and try that.

 

[82355]

and pocket a ign module from the junk yard and try that.

You mean my back yard?

Martin

 

[dyeager535]

If you've got a spare, I'd replace the entire distributor if I was going down the ignition road. These things are old, problems with the reluctor, pickup coil, module, any of that could be an issue. If you've got a known good one, IMO just better to swap it.

 

[82355]

Cable: http://www.gearhead-efi.com/Fuel-In...e-Forum-Buy-ALDL-Cables!&highlight=aldl+cable

I can't help on the type of computer required, but I *think* tunerpro RT http://www.tunerpro.net/ is usable with just about any version of Windows, not sure on the Mac side. I know I've used it with Windows 2000 and XP.

Is there anywhere else to buy the cable? How to I buy one otherwise? I am not a member of that forum. I just want to send someone a check, and have them send me a cable.

Martin

 

[82355]

If you've got a spare, I'd replace the entire distributor if I was going down the ignition road. These things are old, problems with the reluctor, pickup coil, module, any of that could be an issue. If you've got a known good one, IMO just better to swap it.

Yeah, I've already thought about that. This one is out of a '91 Camaro. The OEM one had the distributor gear chewed up by the LT1 cam for some reason, even though it worked with the LT4 cam for a few years. I contemplated just buying a new one, because how do I know if any of the old ones I have laying around are any better.

Martin

 

[dyeager535]

I'll try to get you contact info. I don't think you can get them any cheaper somewhere else. I'll PM it if/when I get it.

 

[dyeager535]

Good time to check and see which of your "spares" are ok.

I know it's some work, but pointless to have unknown quantity spares laying around. You'll know if you fixed it or made it worse, immediately at least.

 

[80' 427]

Plus those tbi style dist like to wear out worse than the old HEIs. I would just get a new NAPA one.

 

[82355]

I just ordered a fuel pressure gauge and tap, and an adjustable regulator. Should be here in a few days.

Martin

 

[82355]

I'll try to get you contact info. I don't think you can get them any cheaper somewhere else. I'll PM it if/when I get it.

Yeah, it wasn't the price I was so much worried about. Is this what you use? I'll only be using it on TBI rigs. I looked like there were some different options?

Martin

 

[82355]

Good time to check and see which of your "spares" are ok.

I know it's some work, but pointless to have unknown quantity spares laying around. You'll know if you fixed it or made it worse, immediately at least.

It's not so much that I have spare distributors sitting on a shelf. I just cut up a lot of old rigs. I have several complete TBI engines sitting around that I could steal a distributor from.

Martin

 

[82355]

Plus those tbi style dist like to wear out worse than the old HEIs. I would just get a new NAPA one.

Would you trust an Echlin module?

Martin

 

[dyeager535]

I think he's getting at replacing the whole distributor. Last I heard they weren't that much, but generally aftermarket ignition products are junk compared to GM. $102 at my local napa, Part Number: NRD 481830




ALDL cable will work on any of the GM OBD1 stuff, looks to me like the design is just a bit different. The "switch" allows you to use it on certain OBD1 applications that require resistance to get the data flowing. For instance, the ECM used in the '85(?)-89 MAF F-bodies. Again, not a big deal if you don't need it, but it's there if you do.

*IF* you think you are ever going to get into tuning your PROM's, it's a better idea to step up to the equipment now, especially since some setups come with the ALDL portion. If not, just stick with the cable of course. Cheaper.

 

[82355]

I think he's getting at replacing the whole distributor. Last I heard they weren't that much, but generally aftermarket ignition products are junk compared to GM.

Yeah, that was my thought as well, but if you buy a Napa distributor, it is going to come with an Echlin module, not?

ALDL cable will work on any of the GM OBD1 stuff, looks to me like the design is just a bit different. The "switch" allows you to use it on certain OBD1 applications that require resistance to get the data flowing. For instance, the ECM used in the '85(?)-89 MAF F-bodies. Again, not a big deal if you don't need it, but it's there if you do.

*IF* you think you are ever going to get into tuning your PROM's, it's a better idea to step up to the equipment now, especially since some setups come with the ALDL portion. If not, just stick with the cable of course. Cheaper.

What are the price differences? I do have a complete 350 TPI sitting in my hog barn.....

Thanks for your time by the way.

Martin

 

[dyeager535]

I suspect it would be echlin, yes. Sometimes you just get stuck using "inferior" parts, no two options anyway. And sometimes people just can't justify the GM price.

This is what I got: http://www.moates.net/apu1-autoprom-package-usb-version-p-54.html?cPath=95

Others can probably chime in, once I got that I pretty much stopped paying attention to other options. I spent that much money, I better get my use out of it. So far though it has allowed me to work on my Dads truck, and mine, so it has certainly paid for itself.

 

[82355]

That's more than what I am interested in at this time, but that doesn't seem like a bad price.

Martin