Driveability issues

[ZephTheChef]

Picked up a project Festiva yesterday. 107,000 miles...decent shape outside, rough inside, and rough mechanically. It clearly isn't hitting on all cylinders all the time and smoking a lot (previous owner thought it was burning oil)... and leaking oil everywhere. PCV was all plugged up so I replaced that and changed the oil and filter which greatly diminished the smoking, but still running rough. I pulled the plugs and 3 out of 4 were black as can be, the 4th one was also black but not as bad. Installed brand new iridium plugs, wires, cap and rotor. It runs a little better but still missing pretty badly, pulled a plug back out and these iridiums are getting quite black as well. If revved up to maybe 3000rpm, it smooths out pretty well. On the road, it misses badly at most loads, but if you find the sweet spot it will run smooth for certain rpm ranges and throttle openings. If I unplug the injector harness, the car will idle smooth and steady off of a propane bottle so between that and the other evidence, I clearly have a fuel control issue. Also, compression is 150 across the board, I've played with the timing...more advance seems to help slightly but definitely does not fix the problem.

I am thinking I may have some fussy injectors, but I was looking for some input on that. Are injector issues fairly common on these cars? I know we had some injector problems when we put a salvage yard engine into my buddy's aspire. I don't really know what the exact fuel control scheme is on these cars in terms of what would cause one to run so rich. The FPR is not leaking, the intake is tight and right, the VAF seems to move freely and springs back to closed just fine. I unplugged the O2 to see if it'll make a difference but it doesn't seem to have yet. What do you guys think, do I have an injector problem or is my issue somewhere in the fuel control logic? If it's not the injectors, what all do we have that controls fuel...VAF, TPS, O2, coolant temp, and ECU? Any advice on how to narrow down my problem? Thanks in advance.

[shadetree]

Seems like fuel issue to me as well . Change fuel filter ? And lift back seat and remove fuel pump and clean the sock ! That's just going off your given info . Low miles old car . It's been sitting sometime .
And welcome aboard great first post . Good luck ! You will like it here !

[ZephTheChef]

Seems like fuel issue to me as well . Change fuel filter ? And lift back seat and remove fuel pump and clean the sock ! That's just going off your given info . Low miles old car . It's been sitting sometime .
And welcome aboard great first post . Good luck ! You will like it here !

The car supposedly has a recently replaced fuel pump. Previous owner indicated it had been sitting about 4 months, so the gas should still be good but I intend to pump the tank out and put some fresh gas in anyway just to eliminate that possibility. Filter looks to be factory original, but I can't imagine a plugged up filter would make it run so rich...quite the opposite. I'll change the filter and inspect the pump anyway...cheap insurance.

Thanks for the welcome. Long-time lurker, but I've been a while without one of these cars.

[bravekozak]

welcomsign

I hope you figure out the root cause.
I agree with shade. Remove the fuel pump and look inside with a flashlight. Let us know what you see.

[lessersivad]

Possible fuel pressure regulator.

[Stivadiva]

I currently have an issue with the Idle Air Control IAC) unit, I believe.
Which seems to have similar symptoms to what you are describing, except for the blackened plugs.
Going to replace soon and let you know if that was the issue.

[ZephTheChef]

It does idle awfully high as well. I priced a set of rebuilt injectors...$135 after the core refund. I'm probably going to pull the rail and see what the spray patterns look like...if I have an injector issue, I'll just replace all 4. Will post results...probably will be this weekend, or at least after the holiday before I get another chance to mess with it.

[lessersivad]

Well hopefully i did this correctly and there will be a readable scan attached.




I would also not rule out that someone messed with the idle air screw or didn't, and instead messed with the throttle stop screw in hopes of "keeping it running". Or possibly someone messed with both.

Zeph. You stated the fuel pressure regulator isn't leaking in your original post. Internally and externally?

Did you possibly check for vacuum at the FPR?

I'm simply spitballing from my end. It sounds like you have covered the basics pretty well.

[ZephTheChef]

That's a handy chart. Thanks. The fuel pressure regulator seems to be functioning...I pulled the hose off, capped the port on the manifold and hooked it up to a handheld vacuum pump. I didn't put a pressure gauge in the fuel line or anything, but pulling vacuum on it definitely changed the tone/speed of the engine so as far as a quick and dirty test of the pressure regulator, that was good enough for me. It also didn't spit any fuel out the vacuum port over about a 5 minute period of time so I'm assuming the diaphragm is fine.

Definitely a good thought on the throttle stop...I adjusted the idle screw all the way in and it's still running pretty high at idle. It was definitely running worse before the ignition system tuneup so maybe the previous owner did in fact have the idle cranked way up so that it would run. MOST of the things I'm noticing that are wrong with this car would seem to me to cause a lean condition, not a rich one. For example, the intake hose apparently had fallen apart or cracked at the accordian and it's duct-taped. I added another layer and smoke-tested it for leaks though and it's airtight. Unmetered air entering the system should cause a lean condition though. In my experience with other cars, a bad coolant temp sensor can cause an extreme rich condition.

I happen to have a B3 out of an Aspire sitting in the corner of the shop with head gasket issues. I will do some parts-swapping and see if that gets me anywhere.

[lessersivad]

Yea, the coolant temp sensor would be a good thing to check out. There's also a temp indicator in the VAF area.

I would start with the coolant temp sensor 1st though.

You'll get it.

[ZephTheChef]

Ok, so I pulled the fuel line off to see what the flow looked like. It was moving plenty of gas...BUT the gas was dark yellow in color and stinky. Despite what the previous owner said, I think this car had been sitting a LOT longer than 4 months. I ran all the old gas out, rinsed, and then filled it back up and it runs a ton better. It's still not right...still idles extremely high and no doubt will need a lot of little fixes, but it's not misfiring now and is at least driveable.

[lessersivad]

Glad you found the cause of the misfire without throwing tons of parts at it. Good job.