Need Help, RPM Surge.

[Quirk]

Alright let me explain my issue here.

Replaced the IAC/ISC yesterday. I am driving down the road I made it about ~20miles until it started to surge. RPMS will bounce up/down then car will turn off. Sometimes car wont start backup unless I unplug the sensor, plug it back in. So I really had to get it back home, I was driving, everytime I felt the car kind of shake and when I feel the gas pedal isn't responding, I don't hit the gas and coast for a little and I just put my foot back on the gas, the car is fine.


Engine Codes:
Malfunction Fuel Trim
cylinder 2 random/multiple misfire

I am starting to think its the FIAV or crank angle sensor?
Please help me.

 

[the_mork]

The fuel trim malfunction means most likely that your o2 sensor has gone bad or you have a significant vacuum leak.

I'm not sure what to think about the cylinder 2 random misfire, check your plug, wire, and coil pack.

I don't think this has anything to do with the TB.

 

[slickers111]

You have a good idea on checking the FIAV, but also check the O2 sensor, and the MAF sensor. Also make sure that all your hoses are connected.

 

[Quirk]

You have a good idea on checking the FIAV, but also check the O2 sensor, and the MAF sensor. Also make sure that all your hoses are connected.

What tests can be done to figure out which sensor needs to be replaced?

 

[DSM4me44]

Sounds like you have a bad plug or wire on 2. As far as the surging, you could have a leak at your TB or your BISS screw.

 

[Quirk]

Damn everyone has a huge list of things to check out, The misfiring does not occur until the rpms start surging. Sometimes I can make it ~20 miles before surging, then engine really misfires badly.

 

[the_mork]

IMO it sounds like you are going either too lean or too rich on that cylinder.

Here are the steps to diagnose and fix your problem.

Do a boost leak test. This is absolutely the most important step.

Fix any boost leaks.

Drive the car around and see if your problems have gone away.

If not,

Buy a bottle of Seafoam. Unhook a vacuum line and insert it into the bottle while the engine is running, the engine will try to bog down but let it suck in a few tablespoons. A thick white cloud will come from your exhaust, if there is a significant amount of exhaust coming out before your o2 sensor then you should fix that leak otherwise you are done with this test.

If your problem is still not fixed then purchase and o2 sensor socket and a new o2 sensor. Search for the best deal, I found a snap in replacement for $62 locally but most people have to go with a universal replacement for about $75.

If you are relatively confident that you don't have a huge exhaust leak before the o2 sensor you can skip the step with the seafoam but with the fuel trim malfunction you have probably been running super rich and should use a bottle of seafoam after you have your problem fixed anyways. Do a search for Seafoam if you are unsure how to use it or why.

 

[slickers111]

What tests can be done to figure out which sensor needs to be replaced?

I am not exactly sure on how to test all of those.

 

[Quirk]

This car is pissing me off I guess this is my welcoming to the dsm world.

 

[the_mork]

This car is pissing me off I guess this is my welcoming to the dsm world.

The best way to bump your thread as well as provide the sort of information that allows us to help you is to take the most recent and informative post, quote it and respond to each part individually, if there happens to be several informational posts that you have not responded to directly yet then quote each of them, if you weren't aware the quote function is very easy, just use these tags,

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