IRocN87

Hi all, I've been playing around with my car (87 305 tpi auto) for some time and have not been able to have it running well recently. When I start it, it idles perfectly fine, and is very responsive to the throttle. Idles well in gear too. However, as soon as I put it in gear, AND give it gas to move the car (in drive or reverse), the car runs like crap. Bogging, sputtering, weird RPMS. Sounds like a big ol cam, but it's stock internals. Putting it back into park or neutral does NOT help, and the only way to get it idling properly is to restart my engine. It is so bad that it is not at all drivable atm.


Things I've tried: Cleaned and set the IAC/TPS, fixed / tested all vac lines, cleaned TB, tested brake booster (had a leak which braking caused the car to stall, but my hose going to the check valve was cracked --> now repaired), new plugs and wires (tho, it idles fine until moving), new MAF and burn-off relays AND new maf sensor (this fixed a really bad bogging issue I had whenever I gave the car gas), new heated O2 sensor. I'm sure I'm forgetting a few other things too.


Any ideas on where to look? I'm stumped. I have an old accell ignition coil (I've read people have problems with those), but I have a feeling the issue is more air / fuel related due to the symptoms. Any advice would be appreciated.

Vader

Weak spark can allow an engine to idle just fine but suffer spark blowout (extinguishing) under higher cylinder pressures, a.k.a., load.

Low fuel pressure in an injected engine can exhibit similar symptoms.

IRocN87

Thanks for the input. I just put on new plugs and wires 1000km ago. Weekend bucket list: clean out injectors, replace fuel filter, try old spark plug wires. If all else fails, I'll replace my janky ignition coil and take a look at the distributor and see what happens.

Will update with results.

IRocN87

Been busy, but time for an update:

Replaced fuel filter, tested + cleaned fuel injectors, replaced fuel pump, and replaced ignition coil... Still giving the same issue. When in gear, and given any amount of gas, it runs like crap or just flat out stalls.

Getting tired of throwing random parts into it thinking it may be the issue. I guess the next thing would be to focus on spark and make sure everything is checking out.

Where should I look? Given that I can give the car all the gas I want when in park or neutral, can I assume my plugs and wires are good? Or should I consider changing those out too?

Lastly, my battery has been hurting from all the starting and stopping without getting properly charged... Any chance these symptoms could be from a bad battery or alternator?

Contractor

Dont know if you are throwing any codes, but my 88 was doing the exact same thing, and I ended up putting a new ECM in it. After a new MAF, burn off relay, etc... chasing the problem. Thinking I was getting a 36 code btw.


Cole

IRocN87

One year later, and I'm still struggling with issues. My car runs "okay" now, but has a ~1s hesitation when giving gas in park at idle. My RPMS actually drop for a split second before increasing. Also my rpms / power / speed seem to lightly (but noticeably) fluctuate at steady cruising speeds.

I've been able to narrow it down to this: My gas pedal becomes EXTREMELY responsive when I start it with my MAF unplugged... As soon as I plug it back in, bogging / hesitation upon pressing my gas is back.

I've gotten tuner pro to try and troubleshoot. I'm extremely novice, but here are some readings that jump out as potentially off to me. All values with warmed engine, in diagnostics mode and idling in park: Airflow = ~2300 (I believe /256 to get ~9g/s? this seems high); BLM at ~108; O2 readings jumping from ~100 - 999.

Switching between my old and new MAF sensors don't seem to have an effect. I'm not sure where to go from here.