Eagle Talon P0171

[Delta]

So driving home from work the other day I was pulling out of a road and it took off and felt like I was in 3rd. Put it in neutral and into 1st. Still bogged and then popped, banged, and misfired till it caught. Now the car will no longer rev past 3400-3500 rpm's. Occasionally it will let me go past it, but most times not. Almost feels like it's running out of fuel. Luckily for me even though the car is a 1995, it's OBDII. The check engine light has been a permanent stable of this car so I had it scanned. The only code stored is a P0171 bank 1 too lean. No misfire codes. Would this be an indication of a failing fuel pump or simply the fuel filter is plugged? The filter looks pretty crusty and likely hasn't been changed in a while.

The car is in time and idles fine. Sometimes it will bog on a cold start taking off and eventually catch. Also if I'm coming to a stop and clutch it, it will die. However it'll immediately start back up. This is the Chrysler non turbo 420A.

 

[Warstud]

Would this be an indication of a failing fuel pump or simply the fuel filter is plugged?

Yes. Or you have an air leak letting to much air into the system. Check the air filter box to make sure it's properly secured and that the tubing is solid.

 

[Delta]

Yes. Or you have an air leak letting to much air into the system. Check the air filter box to make sure it's properly secured and that the tubing is solid.

Hmm on further thought I'm occasionally having issues with it idling way too high, like 2000-3000 RPM's. Also having a massive rev hang. There's some weird goop around the throttle body where it meets the intake. Still don't know why it would be causing it to not be able to go over 3400rpm's unless the fuel trims are so screwed up. Probably have driven over 300 miles since I last unplugged the battery.

 

[Warstud]

Try cleaning the Throttle Body and change the PCV valve

 

[meep]

Limited rpms with popping means it’s running lean. You need to rent a fuel pressure tester and check fuel pressure. Could be a weak pump, could also be a tired regulator if so equipped. If you replace either, go ahead and replace the fuel filter, but I wouldn’t suspect a clogged filter to be the cause.

 

[Eddie]

It almost sounds like the timing belt skipped a tooth. Ed

 

[Delta]

Limited rpms with popping means it’s running lean. You need to rent a fuel pressure tester and check fuel pressure. Could be a weak pump, could also be a tired regulator if so equipped. If you replace either, go ahead and replace the fuel filter, but I wouldn’t suspect a clogged filter to be the cause.

I actually planned to get a pressure tester kit tomorrow, never hurts to have one in my toolbox. It does have a regulator, so that could be something to check out. Is there something that would differentiate that from the actual pump? It will start and idle every time just fine. The engine does lightly pop and bang under decel. I chalked that up to the open exhaust, but maybe not. It also smells super rich sometimes, especially at idle or decel say down the mountain. However, there is no cat on this car.

Also, I did order a new fuel filter. Even though that's likely not the cause it don't hurt to replace it.

It almost sounds like the timing belt skipped a tooth. Ed

I dunno, it will occasionally let me rev up higher. It has always had a stumble since I got it, but nothing to indicate it's out of time. The belt is new, albeit one from Autozone.

 

[ripcord]

Have you looked at freeze frame data? How are the fuel trims?

 

[oggb]

Sounds like it could be a vacuum leak to me.

 

[Delta]

Have you looked at freeze frame data? How are the fuel trims?

I do not have my own scanner, might be time for a cheap bluetooth one. Could really use one in this instance.

Sounds like it could be a vacuum leak to me.

Could also be a possibility. Gonna look over the car more tomorrow once I get a fuel pressure tester. Might have to go around with a can of brake clean to spot possible leaks.

 

[Warstud]

With the car running and the hood open...... stand over the engine and have somebody shut off the car. Sometimes you can hear a vacuum leak for a few seconds after the car is turned off.

 

[cjolson140]

If you have a propane torch, open the valve and hold it near where you suspect a leak, with the engine running. The idle speed will fluctuate if you introduce propane anywhere along the intake that is leaking.

 

[clinebarger]

With Lean Pops & limited RPM.....I'd test fuel pressure first, If fuel pressure is low, Dead Head the pump by blocking/restricting the return line, If the pump can make 90-100 psi.....Theres nothing wrong with the pump & the pressure regulator if faulty.

 

[meep]

Concur. Vacuum issues will cause more trouble under idle and minimal load when the little bit of air has a big impact. When running hard, vacuum leaks tend to disappear into the noise.

a second thing you can try is upping the octane of the fuel to see if you’ve got a hotspot forming, causing preignition. There are other symptoms which come with this, and to me this still sounds more fuel related.

one additional distant possibility is a failing coil or other high tension component. Sparks jump nicely over thin air, but compressed air/fuel mix requires more oomf, and if a component is compromised, the spark will find other paths under load. This tends to show more prevalently under low-rpm conditions, so it’s not where I’d start, though horribly delayed timing raises an eye here, if it lost a position sensor or something jumped a tooth.

if fuel pressure checks ok, I’d look at coil condition, wires, and then cam timing alignment next

 

[Delta]

Ok folks, fuel pressure test done. It appears ok? 40 under idle and revved up will be around 45. Unplugging the vacuum line on the regulator at idle yields about 10 more psi. Could not find or even reach the return line. Here's a quick video.

 

[meep]

ive never seen the fuel pressure bounce like that at idle, but the running pressure at least seems healthy. I would check the other things listed above but have a wary eye on the possibility of an unhappy valve, since that needle bounce appears to be in time with engine rpm and the regulator is biased by vacuum. Compression to test find an oddball cylinder might be the next real diagnostic I’d suggest, but I could be wrong there. Check coils, wires, for arcing?

 

[Delta]

ive never seen the fuel pressure bounce like that at idle, but the running pressure at least seems healthy. I would check the other things listed above but have a wary eye on the possibility of an unhappy valve, since that needle bounce appears to be in time with engine rpm and the regulator is biased by vacuum. Compression to test find an oddball cylinder might be the next real diagnostic I’d suggest, but I could be wrong there. Check coils, wires, for arcing?

Yea it's turning out to be quite the mystery. I took it out for a quick spin and low and behold it ran ok again? It did low key backfire (not loud pops, but lots of rumble so could just be the open exhaust) a good bit letting off the throttle after a 4500rpm pass. Checked for vacuum leaks and there didn't appear to be any. Lots of new hoses so possibly at one time there was. The spark plugs are new, but the wires and coil are what was on the car. It does burn oil on decel and high vacuum loads such as going down the mountain so a couple bad valves are likely. Gonna slap the new fuel filter, PCV valve, and gas cap on when they arrive and call it a day. I'll do a little more tinkering around with it, but decided this car is not going to serve its intended purpose so this is the current state.

 

[NutherDriver]

It almost sounds like the timing belt skipped a tooth. Ed

First thought I had. Check that timing belt before driving that sucker because if it skipped one tooth It can skip another and I don't know how many you've got before your minimum fix is replace some bent valves.

 

[NutherDriver]

First thought I had. Check that timing belt before driving that sucker because if it skipped one tooth It can skip another and I don't know how many you've got before your minimum fix is replace some bent valves.

Time ran out to edit my comment.

Speculation: The pulsation in fuel pressure is a slightly bent valve from a previous skipped a tooth or two. Probably would only require replacing the valves and grinding the seats if that's not been done recently but that's 10+ hours plus parts plus machine shop. My info on this is highly authoritative though I haven't yet posted it under the personal screw-ups thread or whatever it is.

 

[Delta]

Honestly at this point the car is running decent again so it's well enough to sell. Is this the reason I'm selling it? Not entirely, cars just too much nick nacky stuff to do I don't have time for. It's more of a toy than a daily beater. I'll reserve it for driving around town to keep the battery up, but driving over the mountain is quickly killing the thing. I did find a low mileage engine for it for around $300 worse comes to worse. Not the first time I put an engine in this car.