Another Rough/high idle help request.

[Allard3]

Hi all,

Need some advice with the following problem.

About 6 weeks ago the spring in the wastegate failed and I had my turbo reconditioned (by a good company).

Whilst the car was off the road I gave it a birthday.

New PCV
New MAF
New Evap canister
Sump off and pick up pipe cleaned
Rocker cover off and cleaned New gasket fitted due to leak.
Engine flush, new oil and filter.
New seal on vacuum pump

And various other jobs not related to the problem.

4 weeks ago the car was back on the road And run the best it had at ince I’ve owned it.

1 week ago randomly the car started to high idle once it reached temp around 1200. Blip the throttle it settles then climbs to 1200 again. Let it cool down over night jumped in it the next day and notice the it had a lumpy idle and again a high idle when it reached temp (not lumpy)

I’ve removed the PCV again checked the gasket and carried out the oil filler test. With the engine running it’s hard to remove due to the vacuum. So this means the PCV is working?

Next stage will be checking for a vacuum leak this weekend. If there are any tutorials or help with blanks for it that would be amazing.

The thing that is throwing me is it’s both lumpy when cold and high when warm. Most threads I’ve read and one or the other.

Any help or advice would be amazing

[Mark_DF05]

Any fault codes?

There's a few hoses around the PCV that can split, I'd check them for leaks. Not sure of where else to look, maybe someone else can. A smoke test would show any leaks too. Could be a daft suggestion but have you checked the dipstick is seated properly, they break easily.

[brian_badonde]

First port of call would be to see if you've got any soft codes stored that can help you diagnose it. Plug in vcds or obdeleven (you can get them for around £50 including the scanner and a pro license, it's already paid for itself many times over for me) and see what it's saying, otherwise it's a case of guesswork/process of elimination which can take a lot of time and effort.

If the oil cap is hard to open then it sounds like you've got a solid vacuum, although that doesn't mean there isn't a small leak somewhere away from the rocker cover. Check your fuel trim numbers and see if you're running lean, which you can do with a normal OBDII scanner (<fiver off amazon etc). What you can also do is spray a bit of aerosol (like silicon spray, carb cleaner etc) around any vacuum pipes/air lines whilst the engine is running - if you get a sudden change in idle then you know its a leak for sure and take it from there.