Scoundrel

Okay. here's the situation.

The car is an 87 Camaro, the 2.8 has been replaced with a 3.4 with a comp cams k-kit and upgraded injectors. It sputters, dies, and refuses to stay running, generally acting like it's not getting enough fuel. The mechanic who built it had it two months, said it was the MAF even though I replaced the MAF about 5 minutes before putting it in the shop. They said the new MAF I had put on was bad, so they replaced it and it ran.

That night, anyway.

Went to drive it again a week later, same issue. Shop's had the car another month now, still no clue what's wrong. They say it acts like the MAF is bad, but when they replaced it (4th MAF overall!) it still runs like trash, with a bonus of running well (or at least close to normal) when the MAF is disconnected to confuse the issue further!

Have any of you gurus experienced this or know how to fix it? At this stage the car has been in the shop more than it's been in my garage (Or on the ROAD) for the better part of a year, and any help or ideas would be most appreciated.

Scoundrel

Ps: the fuel pump is brand new too.

Drew

iTrader: (58)

Sounds like you might have wandered too far from "home". Meaning the computer might be a little miffed about more displacement AND a cam. It might be able to adapt, but then again it might not.

I'd start at zero and treat it like any other engine that won't run right. With the added benefit of being a new engine that's NEVER run right, I wouldn't assume anything. I'd double check the baseline. Is the distributor dropped in the right place in relation to cyl #1 compression stroke? No vacuum leaks, no overlooked gaskets, no inadvertently left disconnected electrical connectors. Look at the plugs, look at the wires, cap, rotor, look for signs that a cylinder is misfiring or getting too much or not enough fuel. The problem just might jump out at you and be something stupid. If you've thrown 4? 4! 4!!! MAF sensors at it, I'm just going to go out on a limb and suggest that it's probably not a MAF problem. Sounds like someone has tunnel vision and decided that's the only thing it could be, at the expense of overlooking other possibilities like a failed ECM, faulty wiring, a bad connector, or a plethora of potential problems.

Get a copy of the GM Service Manual for your car, and look at the sections that talk about the engine, and general symptoms and what to check when they occur. The book will outline how to logically, systematically eliminate possibilities. The guides in the book even tend to isolate issues without repeatedly throwing MAF sensors at a problem. A new part shouldn't exactly always be the last resort, but it should be close. Very rarely is the first thing you suspect the actual culprit, and resolution to the problem, its usually just a place to start.

drdave88

iTrader: (3)

Time to find a new mechanic too. If he's replacing the same part over and over, he's not competent enough to figure this issue out. Not saying it is the problem, but I might lean toward the ECM being faulty if it runs fine with it unplugged, but runs like crap with it connected. Though, there are plenty of other things to check before going to that conclusion.

Just to be clear, you had this same mechanic build the engine and install it. Everything ran fine when you brought it in. Once he dropped the engine in the car is when all the problems started? Or did you have it back after it was installed and it ran fine for a bit, before acting up? Trace wiring, make sure nothing is pinched, broken, cut, etc. Who knows what may have been damaged during removal or installation.

Scoundrel

Okay, good followup questions.

The car ran well when I had the engine upgraded, and ran well for two to three years afterwards. The poor running is a recent development, and part of the delay is that due to a lack of decent mechanics in the area they are usually swamped. They have an A BBB rating and they are old acquaintances of my family.

Yes, this is the same place that built and installed the engine. Despite what I wrote above, I was tempted to look for a new mechanic, but their familiarity with my car and its upgrades *currently* outweighs that option.

The problem with the poor running started in October. I replaced the MAF on a hunch, put it in the shop, they replaced the fuel pump and the maf again and it ran well for a couple of drives (I only take it once a week, on Fridays, which I wasn't able to do for one of those months between due to some other suspension and third brake light issues) of about 50 miles round trip each. Then it began running exactly as poorly as it was before the fuel pump and maf swaps. It also seemed to drop oil pressure when the rpms dropped to idle, or at least that's my guess because all I have are dummy lights.

Thanks guys. This all helps.

drdave88

iTrader: (3)

OK, it's clearer now, thanks for that. So the swap likely isn't related. Does it throw a check engine light at all? Any codes? The old OBDI doesn't really tell you much anyway, but it might be a starting point. Do you have access to a scan tool to read live data? I'd be curious to see what it's reading for the MAF.

Does it run fine at times and bad other times, or once it starts running bad, it stays that way until some repair action is taken?

Also, oil pressure is going to be lower at idle than cruising RPM, the engine is spinning slower, not pumping as much. A real gauge would tell you with accuracy over the clutser gauge, but that's not abnormal for it to be lower at idle.

Scoundrel

It ran well until the battery died while I was working in the garage, after jumping it is when it began running badly the second time post fuel pump and MAF change. I'm not sure if that's relevant, but that's how it went down. Having never actually seen the Check Engine Light on, which I should have many, many times, I suspect it is burned out. I have LED replacements for the gauge cluster and a replacement gauge cluster with actual gauges, but those are on my work bench and not installed yet so not too helpful lol.

I have a code reader machine, but I did not think to check it before putting the car in the shop since it was running as poorly as it was when I put it in the first time, so I decided they could fix it since they said they already did, which in hindsight might not have been the best idea.

I mentioned the oil pressure light coming on because that was new with the poor running. It had never flickered at me like that before now.

A lot of garages in my town have begun to struggle with 80's and 90s and even a little 00's car repair. They're amazing at anything made before the gas crunch, or they're the kid with the electronics degrees to handle 2010 til now, but everyone around here acts like the 80s and 90s cars were powered by voodoo. Or, in my car's case, Jack Daniel's and bad intentions.

This is all helpful though. If you have other ideas, shoot them. I'll be happy to take them to the shop with me to try to help.

Thanks guys.

GeneralDisorder

iTrader: (1)

Has the shop checked the codes on the ECM?

I'm not that familiar with the 2.8 based cars but I assume this is the 7165 MAF ECM - same as used on the LB9/L98. If that's the case these can have cracked circuit board problems with age. You'll chase tail for a while trying to figure out a cracked circuit board because how runs will depend on the phase of the moon and the wind direction that particular moment. Smack the ECM case with you palm and see if the running symptoms change - might get better or worse. Any changes at all indicates an issue.

GD

Scoundrel

I figure i can necro my own post. After throwing everything at it (IAC, MAF, etc.), the shop relented, listened, and replaced the ECM, and that appears to have solved the running issues. Now if they can just fix the oil leaks and inspect it, i can begin restoring it and taking it literally anywhere else.

I'm going to have fun arguing down the price, i tell you what. All they did was throw parts at it until something stuck. "I" could have done that!

OrangeBird

iTrader: (1)

Of COURSE our cars are powered by voodoo , JD , and bad intentions , , , , , I'll take that over a lousy Prius powered by butterfly farts any day

Sierra6

I've heard that MAFs HAVE to be AC Delco to run properly. Other brands, though expensive and brand new will not work I hear.