Warm restart problems

[ericp]

wow this is making me crazy. i have my 96 ranger with 4.0 in it. it has 184000 miles and has a few things i need to figure how.

1. Truck starts and runs great but after driving and engine is hot i turn it off. when i come back around 30 minutes later to start back up, idles very rough and starts to die unless i give it gas. you can hear in the exhaust pipe that it is missfiring badly. will not stop until i start to drive, it will smooth out slowly. i have changed IACV and nothing. cleaned Mass Air Flow Sensor. new plugs, and fuel filter. (seems problem only occurs in warmer weather) Any ideas?

2. Check Engine Light. Over the past year that i have owned this truck, all of the oxygen sensors have gone bad. most recently bank 1 sensor 1 went out. after i changed it, i left battery off for a while. almost immediatly light came back on. had it checked and came out with codes for the same sensor and bank 1 sensor 2, which i've already changed. both under warranty i changed them and still the same thing. CEL is always on. Any ideas? (since all of this i've driven over 1000 miles, so it would have reset if it was going to)

 

[Jspafford]

Fuel pressure regulator. Floods out the engine as it is sitting and does not have time to vaproize before you restart. It also explains the bad O2 sensors and your probably horrible fuel mileage.

It is located on the top of the valve cover and will have fuel lines going into and coming out of it. It will also have a black vacuum line going into it. Pull the vacuum line and check for raw fuel.

 

[ericp]

any other ideas? fuel pressure is fine and there is no raw fuel in line

 

[Jspafford]

any other ideas? fuel pressure is fine and there is no raw fuel in line

The fuel pressure on the rail would be fine. The FPR's have been known to be bad and not have fuel in the vacuum line.

 

[MAKG]

No code condemns any sensor. Lean codes MIGHT be due to a hosed oxygen sensor, but it's not very likely. I still have original HEGO sensors (both of 'em) in the Prizm and they work fine. I test them before every smog sniff (2 years).

Lean codes are not easy because there are a LOT of potential causes for them -- even a RICH misfire can cause a lean code.

You need professional diagnosis. For one thing, OBD-II codes "reset" after a drive cycle. It is possible to drive 1000 miles without completing one.

 

[Bruce]

Engine coolant temp sensor can cause some rich or lean fuel problems also. Like MAKG said you need to get it scanned by a professional, that way the can look at the data stream while its runnig and see whats going on.

 

[Jspafford]

Engine coolant temp sensor can cause some rich or lean fuel problems also. Like MAKG said you need to get it scanned by a professional, that way the can look at the data stream while its runnig and see whats going on.

When my sensor went out the truck would flood out and not start for a couple hours. I also noticed it has began to idle about 300 rpm higher than normal right before it stopped starting and I diagnosed it.

 

[ericp]

Ok, i got a new FPR and everything is the same. what is another possibility?

 

[copperranger]

I'm having similar problems. I'm wondering if it is the injectors themselves. My ranger has 170K on original injectors. i don't know how long they're suppose to last but when the filter was changed stuff would fall out if you hit it on the ground. could that have killed the injectors?

 

[SoLongStang9499]

I had a similar problem with bank 1 sensor 1 on my ranger. My co worker, who is a full time mechanic, told me that if you are to replace an oxygen sensor on any given bank, you are to replace all the sensors on that bank ( so sensor 1 and 2 of bank 1, which is the 2 sensors on each header).Otherwise, he described that if you replace a bad sensor ( say sensor 1) with a new one, the ECU will compare the new sensor to sensor 2 and believe that sensor 2 is now defective. Maybe this is incorrect for rangers, but I went and replaced both sensor one and two at the same time, and havent had any problems since, all other sensors work as they should. Just passing the word.

 

[289-tiger-]

Are all of the ignition components visible (i.e. plug wires) in good condition?

Vaccum lines and lower intake torque ok? Try plugging the ports one at at time. If it smooths and quiets out after running I wouldn't think anything mechanical came unglued. Ended up replacing my MAF. Hope this helps.

Good luck

 

[shadetree]

Take a look at your engine coolant temperature sensor and circuit, as previously suggested. This is the automatic choke for fuel injected cars. Another sensor that will cause hard starts is the throttle position sensor, and it sometimes doesn't give a code.

But, Gross is right, have the codes scanned. You will waste a lot of money throwing parts at it haphazardly. shady

 

[parson2008]

mine was doing same thing, it wasn't fuel pressure reg, or coolant temp sensor. it turns out its a bad head gasket, its a tiny leak, my truck you can barely tell it has one but the coolant is barely leaking into the head enuff for it to misfire but after 30 seconds or so it idles normal

 

[F150hybred]

Hmm... interesting read. I'm having a similar problem with my 94.
Symptoms: full opperating temperature... Turn engine off and go in to the 7-11 for a minute, come back out and no start. It does TRY to start, but it won't. If you leave it sit to cool off, it will start.

Observations: if you depress the fuel rail schrader, it seems to be "air locked". Nothing but air comes out. FPR, Fuel filter and fuel pump check out and were replaced if necessary.