I am new here and have posted a few times before since I bought my 2001 1.8T AWD engine code Jetta.
The issue I am having is this. (a bit of a read. No really its long)
The previous owner warned that a EPC would come and go but no CEL
I thought ehh its worth it, I want a jetta and this is a good deal.
Car ran fine for the first few weeks, but I wanted cool pshh pshh sounds, So a gentleman on JJ hooked me up with a brand new forge DV spltr.
I installed it in about 5 min and set it to 12 clicks (guys at forge said this was a great starting point) it ran fine.
Then one morning I went out to start it and it was idling all over the place and scared me, my mysterious new Jetta was messing up and I have been living under a rock since I was 11 years old I owned a 76 camaro z28 and a 94 mustang with a custom supercoupe swap and I built both of these, so diagnostics was a cake walk.
I called a shop in town they were a huge help over the phone and I eventually took the car to them and they were able to diagnose a boost leak, implausible signal issue to TB and faulty PCV system. Before taking it in I replaced the stock DV just to see if they would claim it faulty.
800 dollars and about 2 weeks later I had my Jetta back.
It drove great, I started to notice a small thump from the exhaust as the days passed so I had a set of coils/plugs that i ordered from ECS and decided to throw those at it.
I have noticed the small thump since mostly in the mornings and only at idle.
I was driving at one point and a EPC and check engine light came on and I returned to the shop to have it read. I was told it would be a few weeks before they could diagnose and that it was a static vac leak and pressure loss between turbo and TB valve.
I decided since I eventually want to get a APR tune I can just go ahead and install my boost gauge, and it can help me see if there are any needed adjustments on the DV and also be able to tell if i go in soft limp before the EPC pops on again. i went to soft limp a few times over the next couple days. i also noticed a very eratic needle during vac. at idle. boost didnt seem to get quite past 6.5
I also while under the hood at some point after, noticed fluid at the base of the injectors oily substance (thought to be gas). I made my way down to the parts store and purchased O rings after a quick Google and confirm of these causing such a problem. I changed the upper o rings and left the lower due to the fact that the lower o rings are not easy to find in parts stores, at least they aren't listed.
I did however soak the used ones in some synthetic oil to liven them up till i can find the proper part number.
The night I changed the O rings I went to a 311 concert about 55 miles from home, After the concert I was ready to leave cranked the car and the idle was horrible fromt 2500 to 600ish and the EPC ASR and CEL were illuminated.
I panic'd a bit stared under the hood for a while and decided to cycle the ignition on and off a few times, this seemed to work I was able to get a somewhat decent idle and make my way through the traffic before it popped the epc in which case i pulled into a lot and let it clear.
the next day it started up and idled rough but got me to work, on the way home I had to hold my toe on the gas to keep it running at stops and when stopping (not easy in a manual) or it would die out. I called the mechanic at the shop and made arrangements to bring it in that evening.
On the way to the shop it was a gem I questioned having to take it in, but decided it best for the long run.
4 days at the shop and they made time for me, claimed the throttle body was now the problem and they could not diagnose the static vac leak or pressure loss due to modifications. (begin small rant) Now I don't consider a boost gauge and a DV too drastic a modification but the owner made it very clear he had no interest in finding the issues and even recommended a shop one town over. I am not upset at all about them not being able to find the issue but to blame it on the Mods? really?
(end small rant)
So they replaced the TB and set the readiness codes while I was in school today and my GF was able to go by and take care of the bill and get the keys.
Tonight we picked it up and I get in and it starts up great and then about 5 seconds of running....... CEL...... seriously and then oh yeah they didnt want to trace the vac leak issue.
it just sucks to have invested 1400 in repairs and feel as though I got no where.
the car seems to idle fine (very small variation, when stopping it will drop down below 800 and then return), gets full boost and has plenty of power, it just that CEL is going to bugg the mess out of me.
So where should i begin diagnosing the issue, and does this seem like the tail tail signs of anything other than me being a noob and not knowing enough about the platform. i have very limited access to vag com via school (NTI) and will also be inquiring with an instructor about some pre class fun in the lab with this.
And if you read all this, You are a trooper thank you for helping. I will have the CEL codes read in the morning and update this to confirm the CEL is a vac/boost issue.
again Thanks for reading and any advice is welcome