prime

Right so the rundown, 1988 FC GXL, ran good until the recent problem. Has been used for drifting, but generally babied when street driven. Doesn't leak oil, doesn't lose much for the driving either.

Currently having some odd starting and running issues. When starting first thing in the morning (external temperature cold), it'll start and catch, but won't rise above maybe 1200. Putting the foot on the gas results in this sort of choked, hollow sound, and it revs down until it catches at lower rpms again, then cycles through the choked hollow noise if you keep your foot on. The more gas you add, the deeper said sound becomes.

Running, it usually runs fine, but will occasionally have a prolonged and quite distressing fit, where-in the engine just stops producing power. Or engine noise for that matter, and generally a few moments later will kick in again. Sometimes it cycles very quickly, sometimes very slowly. Occasionally you get only one or two and then it seems fine. Sometimes for weeks.

The starting issue is usually overcome by using the deflooding proceedure, only when planting the gas and starting the car will it rev above 2000. And then you need to push it really hard, round 5000, until the odd hollowy/wet noise clears, otherwise it just goes back to the same thing, or stalls outright. After the noise clears its fine though.

Thats about all I know about it, I've been through the car checking for loose grounds and such, and I've not found anything. If you know a specific ground, feel free to point me at it and I'll check it. I'd even disconnected a few, cleaned the contacts, and reconnected them. First one I tried was the fuel pump, few friends seem to think the pump is dying.

I'm not so sure myself, the issue has been known to turn up whether I have a full tank or I'm almost empty, and save for when it turns up the car purrs like the proverbial kitten. Full tank or no.

Any help or idea's would be appericiated. Thanks for much.

Also, I have a Hanes Manuel, best I could get, but if you want to point me to a specific page number you've known to be helpful in the past I'd appericiate it.

AGreen

iTrader: (11)

Check your compression first of all. Once you've verified a good base engine, we can move forward with other diagnostic testing.

While the spark plugs are out, check the wear and color.

Rx-7fetish

Change fuel filter. And check filter sock in tank. My car acted just the same. Turned out sock fell off and sucked trash up and was clogging my filter and jamming my pump. It was kinda large chucks that would on occasion stop up the filter and when it would studder the pressure holding the chunk there would drop, it would move and the car would get fuel again. Chased that issue for 3 months. Final straw was car dying on high way on way to see mom in hospital for surgery on possible cancer. Very crappy day.

Rx-7fetish

The deflooding worked I think because it was relieving the pressure on the filter and letting the chunks loose and out the way.

prime

Honestly, the fuel sock being messed up was my very first theory. Slightly ashamed to admit I never checked it, since other more experienced individuals were pointing me in other directions. My face is gonna be red if thats the issue. There's also a suggestion that its still a bad ground, but the wire inside is split or bad somehow, so I guess I'm gonna check the grounds.

If this doesn't work, I'm gonna start collecting parts to swap this **** to carburated. -_-

I want to eventually anyways.

Rx-7fetish

I would still replace the filter in bay and the sock in tank regardless if the sock fell off or not. Filter might be the original if you have never changed it. Cheap enough to to and prolly needs to be done anyways. If that is the issue and you switch to carb without fixing it you will still have the same problems.

Rx-7fetish

I have also noticed while more experienced individuals know what they are talking about they tend to jump to worst case/most expensive problems first.

AGreen

iTrader: (11)

I've noticed that (and seriously, no offense) less experienced individuals jump to conclusions because they had a problem like that one time, so this problem has to be the same. A compression check is simple, and is the basic foundation for any troubleshooting with a rotary. Once you know you have good compression, you can move forward to checking other things. A clogged fuel filter or in tank sock is a possible cause, but usually it's not an intermittent problem like is being described here. It does sound like an airflow meter issue, like it's getting hung up internally, but I don't like sending people down a wild goose chase, I prefer a more logical approach to troubleshooting.

If maintenance has been neglected, by all means take care of it first. However, I've seen only a few cases where performing routine maintenance has fixed an intermittent problem.

prime

Compression was fine last I checked, that was a couple months ago though. Still, as previously stated, it'll run fine for weeks maybe, and then for a little while its bitchy as hell. Right now I can't even get the RPM's to raise over 1200, foot on gas equals loss in power. She won't move. I'm gonna pull apart the fuel pump tomorrow and check the sock and such. If it has fallen off, thats easy enough to fix, and I'll be happy. If not, well, I'll have to check all the grounds with a voltmeter to find out which one is wrapped around a bad interior, because I've checked/cleaned the contacts where I could find them/where they've been suggested.

Suspecting a wire is bad puts me back at square one basically, but then I should've checked the wires when I was mucking about with the contact ends anyways.

On compression, I've got three even spikes in both rotors, or had. They should be fine, I don't see any reason why they wouldn't be. I don't let her run out of oil, did an oilchange pretty recently too. Runs fine when she wants to, pulls hard when she does, and drifts when she's bidden. Whatever the issue is, I think it's safe enough to say its connected to my engine, but not the engine itself.

The interior of my car is stipped btw, if anyone could think of a reason that makes a difference. Maybe I should check the wiring back there, to see if a bit of wire could occasionally make contact with the frame anywhere. If its going back to the fuel pump, I could have a short ground screwing with me, perhaps.

Not to dismiss your air flow meter idea, I'll see about testin it.

Rx-7fetish

I was just saying check te simple stuff before he jumps to shorts in his harness and other hard to chase issues, compression check, cool its free, but generally a motor with bad compression runs bad all the time. If he waits until it is studdering to check compression of course he will get low numbers at that time. Fuel sock is also free to check, if the fuel sock is off or clogged chances are pretty high that the fuel filter is also needing replacing. Quick simple stuff to check. I'm not just jumping to it because it's happened to me before, and I wouldn't call myself inexperienced either. No I'm not a mechanic by profession but it's what I do to make a little money on the side, all my friends are almost all ase certified and one of them is a retired master mechanic for gm, they all agree on a fuel system issue. I could also suggest spark plugs but from hi description of work to car I would assume he keeps up with regular maintenance such as plugs an oil.

AGreen

iTrader: (11)

I am an ASE certified mechanic. Not knowing compression is like going to the doctor with a problem, and they don't take vitals.

Compression check's been done at least, so we're not worried about that any more. I don't know the age/health of your engine, so if I'm trying to point you in a direction, I need to know these kinds of things before moving onward. Anyways, like I said, it's a possibility that the fuel sock/filter could be clogged, but if any maintenance has been neglected, now's the time to catch up on it (i.e. fuel filter, check spark plugs, etc.) Intermittent problems are always the worst to diagnose, and are even harder to help someone without seeing the car in person. If it's a hard fault, a multimeter could find the problem in minutes, but seeing as it's intermittent, you're going to be in for a fun time trying to find this thing.

Try swinging the flapper door of your AFM to see if it's getting hung up. If it's not moving 100% smooth, it's quite possible that's the problem. Those things were calibrated way back in 198x, so after 20+ years the rheostat inside could be getting worn out, the flapper bushings could be going bad, or just about anything you can think of. Another thing you can do is go through the engine harness and do a wiggle test. Grab the harness in various locations when it's having these issues and see if it gets cleared up when you move a certain connector.

One quick question about your deflooding method. Are you saying that you're deflooding it by pressing the accelerator to the floor, or by actually removing the EGI fuse and cranking it and/or putting oil in the engine to build compression? S4 ECUs don't have a clear flood mode, so by flooring it, it's not doing anything, and actually might be injecting more fuel due to the higher airflow the AFM sees, or the larger throttle position.