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I have an issue with my truck that has been happeing over a year now and it will not throw a code. When in park it will sometimes start sputtering and if i give it gas it will backfire through the throttle body. I can wait it out or floor it and it will stop. Either way after it quits running rough I can hear the IAC valve hissing like hell and if i put it in drive while its hissing it will try to lunge forward. I’ve had all sensors replaced for the hell of it and tried to check for vaccum leaks but no luck. I meant to add, this might happen once a week or once a month. I have seafoamed and used several gas treatments. I’m going to buy a fogger and smoke test the engine soon.
2000 3.9 dakota 203,000 miles.
I can’t remember if I asked this before so if I did you can feel free to erase it.
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So far it doesn’t matter what the temp is. I will swap sensor out to see since I bought the cheapest one last time.
Replaced the Coolant temp sensor and IAT sensor and it did it a few stop lights down the road. Can’t wait to get smoke machine and check engine.
How do the plugs look ? oil fouled at all ? check that the pcv valve is working properly. next – remove air cleaner , open throttle body and look inside the intake man with a good light. see wet oil pooled in the bottom of the intake ? if so you have a blown lower plenum gasket which can cause the probs you described.
Plugs are new Iridium, it did this before the plugs. Wires are new 8mm msd wires. I haven’t thought to check the gasket you are talking about, I thought if i had any kind of bad gasket internally there would be smoke coming out the exhaust. PCV is fine. I have seafoamed engince with 2 cans over the last year with a small hose setup like a IV drop so engine never died or hydrolocked.
I haven’t checked yet but I do think engine might be pinging and thats a sign of plenum gasket. I had a loud chattering at first when my auto tensioner was weak and it would click. Installed new 15.00 one and it went away even when a/c is on. Now at about 65-70 i can hear almost the same sound except it seems to come from driver side of motor and tensioner is on passenger side.
Issues like this are often fuel or ignition related. It’s easy enough to do a tune up and it sounds like you’ve done plugs so far. This leaves a mixture problem. I’ve never seen Seafoam cure a fuel delivery problem. Also, if you have a vacuum leak as suggested, Seafoam will have no effect. I’d recommend checking for vacuum leaks at the intake gasket.
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
I’ve tried about all I can. I’ve soaked just about every part of the engine while it is running and can’t find a vacuum leak. I sprayed the lines with starter fluid and sprayed around intake. Going to smoke engine soon. Currently replacing all front end bushings. Fuel pump is also factory but i’ve been told they hardly ever go out on a dodge.
Do you have a scanner to read live data? would like
to see fuel trims and timing. You might have a stretched
timing chain. did the old plugs look clean?Sounds like it has a fuel delivery problem. The PoP in the intake leads me to believe it’s not getting fuel and your hearing a lean backfire. When the engine starts to die off the IAC tries to compensate and when the engine speed returns to normal the IAC needs time to readjust the idle speed.
If I was a betting man (and I’m not) I would be betting on the Auto Shut Down relay or Fuel Pump relay is going bad. It’s a cheap repair so you won’t go broke replacing them.
At 203000 how many times have those relays turned on and off?
I’m only guessing however. The problem could be a fuel pump issue also.
I don’t have a scanner but I will try to get my hands on one. I hope to check the relays soon. Thanks for all the suggestions.
[quote=”syllinx22″ post=74922]I don’t have a scanner but I will try to get my hands on one. I hope to check the relays soon. Thanks for all the suggestions.[/quote]
keep us posted on your progress. 🙂
I got an older autoxray with almost all the cables for other vehicles etc. It just doesn’t support live viewing of data till i update it and that means I have to find the usb cable for it. I’ll get model number today and see about ordering usb cable.
Update-Just realized that everywhere I try to order usb cable they are discontinued. I also noticed today that when it started it’s stalling and i gave it gas while idling i could hear tapping. Wondering if a valve or something gets stuck at idle.
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