fuel cut, stock boost

[talonDSMerr]

when i bought my car, the owner said there was a boost leak that he couldn't fix, so i bought it thinking i could fix it later. there was a check engine light and i was told it was just for emissions.

i drove the car around like a granny but whenever i did step on the throttle, the car would start bucking. so about a week ago, i took it to a shop to fix the boost leaks and changed the spark plugs. still bucks. after that, i took it to a local shop to diagnose the CEL and they said the ecu was throwing codes 13, 14, and 25, so something is wrong with intake air temp, tps signal, and barometric pressure sensor.

i was thinking it might be a bad maf but would that throw the tps off as well? i am going to try putting in another ecu to find out if that is the problem this wednesday, but any ideas to other causes of this? any one else have a problem similar to this?

thanks for any help in advance

 

[Gstclipse69]

I would start with replacing the maf. Look in the classifieds and get another 1g maf. If the maf is bad then it could be relaying to the ecu the incorrect airflow, therefore the ecu is dumping in fuel and then your getting fuel cut ( the bucking ). Also I would make a boost leak tester yourself (10 bucks) and check for boost leaks. I wouldnt ever trust a shop to fix all boost leaks.

 

[talonDSMerr]

i'll look for a 1g maf and see how that changes anything.

today, my car was idle surging even after it was all warmed up jumping like 500 rpm... i am guessing that has to do with the TPS?

 

[Gstclipse69]

Idle surge can have many many culprits.
http://vfaq.com/mods/wayback/BradBauer/engine/surge.html
Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

 

[FP3065TSI]

i had the same problem! turned out to be the maf sensor.

 

[talonDSMerr]

wow awesome! i'll order a used one tonight, i knew somebody on here must have had a similar problem. thanks!

also thanks gstclipse for the links, although a bad maf wasn't among the reasons for idle surge..? i will check those if replacing the maf does not work.

 

[talonDSMerr]

well, I replaced the MAF a couple days ago and the problem hasn't been fixed, although it does run much better. Still, at highway speeds when I try getting on the gas, it will stutter every time. The car still idle surges but now only does it when it's warming up.

I don't think my ISC is the problem, as I read throught those links and the symptoms don't match up. Also, my BISS and o-ring was replaced as well. I'm beginning to think there is something wrong inside the ECU.

 

[Gstclipse69]

Has the car thrown any more codes since you installed the maf?
You said the shop replaced the plugs, did they use ngk bpr6es plugs? Are they gapped correctly at .028? How long has is been since the plug wires were replaced? You could also check the coilpack. Search for coilpack on here and a couple links will come up telling you how to check them.

 

[talonDSMerr]

Yea, a CEL still comes on. I haven't had time to take it somewhere to read what they are though.
The shop specializes in DSM's and put in the NGK's gapped at .028. Plug wires have not been replaced but they said they can hold up a while longer. I don't think it's the wires or coilpack because it's like i'm hitting fuel cut, not just hesitating. i'm gonna try replacing the ecu over the weekend.

Thanks for the input.

 

[talonDSMerr]

Well, I replaced the ecu with one from a perfectly running car and drove it around the block and it still comes up with a CEL. So far, I've replaced the MAF sensor and ECU. I'll be going to radioshack to get a buzzer and find what codes my ECU is still throwing later today. Right now, I'm assuming it is bad wiring that is causing this.