Help / diagnosis needed

[Paul_A]

A liitle help needed here!
Been suffering from an incredibly Lumpy idle for a while now occasional stalling too!
Replaced the iac valve and throttle position sensor but not a great improvement!
Just put an OBD reader on and got the following:

Calc. Engine load Min 2.74% Max 3.92%
coolant temp Min 172.4f Max 172.4f
short term trim 1 Min 66.40 Max 66.40
Long term trim 1 Min 23.43 Max 23.43
short term trim 2 Min 84.37 Max 56.25
Long term trim 2 Min 23.43 Max 23.43
Fuel pressure Min 765kpag Max 0 (?)
man air pressure Min 9.715 psi Max 12.615 psi
RPM Min 913 Max 1170
ign advance Min 7.5 deg Max 18.5 deg
intake air temp Min 80.6f Max 80.6f
Air flow Min 3.28 g/sec Max 5.57 g/sec
Throttle pos min 0 Max 0.39%
02 sensor 1 min 0v Max 0.02v
02 sensor 1-2 Min 0v Max 0.445v
02 sensor 1-3 Min 0v Max 0v
1-4 min 0v Max 0v
1-5 Min 0v Max 0.025v
1-6 Min 0v Max 0v
1-7 Min 0v Max 0v
1-8 Min 0v Max 0v

Also throws up occasional p0121 and P0122 codes as well!
Only thing I can think of is that I lost the screw in gas cap and it has a temporary push fit one on there....... surely not??
I'm thinking maybe Intake manifold gasket (s)??

Thanks in advance!!

[Ebenezr]

I'd love to help you but I have not even fixed my own yet after 5 weeks and several mechanics. I have replaced a lot, unecessarily. I tore my intake off today to replace the gaskets - a common problem. I did find a problem spoken of in the manual: on 2 injectors the O rings were ruined...mushed. This allows unmetered airto enter around them. Just remember the axiom: Common things occur commonly.

[VXR]

I'm thinking maybe Intake manifold gasket

that would be my first guess for 3.5

[Paul_A]

that would be my first guess for 3.5

It's the 3.2... but I think they suffer too?

[mantis465]

just a guess without actually looking at it but have you checked your valve clearences? tight valves can cause a rough idle and stalling, or made sure that your egr is not stuck open... the egr would most likley set a light but you never know. mass air flow might be dirty clean the wire, also have you done any work on vx latley?... did problem just happen over night or has it be progresssively getting worse?

[Paul_A]

Hi,
It seems to have happened (got worse) since I lost the screw in gas cap and replaced it with a push fit one. I've cleaned the EGR (even tried blanking it off) cleaned the Maf, replaced the tps and iac. There's a high pitched whistling sound coming from somewhere which I'm thinking is air rushing in ... gaskets or vaccuum leak. the only other thing I can think is it might be the fuel pressure regulator.. Might replace that with one of these:

http://www.ebay.co.uk/itm/UNIVERSAL-...item53e8e3881d

What do you think?

[mantis465]

if you think you are able to hear a vacuum leak there is an easy way to test for that. with motor running spray something flammable like cold start, or intake cleaner around were u suspect vacuum leak is (be sure not to spray to close to were engine actually intakes it air from or it will give you a false positive) if the rpm changes then you know you have an intake leak and were it is comming from. the traditional gas to use is propane but with the vx intake plenoum design it will be very hard to use because it is light than air. i really think before you throw anymore parts at it you need to do some real diagnoises, i also think you should be checking your valve adjustment like i allready said. and if you think it is your fuel pressure regulator then hook up an external guadge and see what you have for pressure, keep in mind that at idle fuel pressure in the line is lower due to low pressure in intake

just my 2 cents hope this helps

[Paul_A]

Hi Checked the valve clearances... all seem O.K.
Gonna try spraying around the engine... what would you think would be better? wd40, carb cleaner or easy start? I think easy start is the more "flammable". One thing I did try was putting some cling film over the gas tank neck to temporarily seal it. Not sure, but I think it helped a little!

[Y33TREKker]

I think what mantis meant by saying flammable was to use something like ether or easy start, because if it got drawn into any vacuum leaks a change in idle speed would be recognized. While I'm not sure if carb cleaner would necessarily be harmful, I will say that I don't think you'd want to use wd-40 for what mantis was suggesting.

I'm not sure at this point what other suggestions to make, but will keep it in mind.

[Vinnybin]

I also have a rough idle. I'd like to check valve clearances but the service manual isn't quite dumb enough for me. I can't find a how to or thread on it. Will someone help me out?

[Dmitrikr]

eeehh hisssing noise - vac leak. on mine was cracked intake gasket.
short term trim 1 Min 66.40 Max 66.40
Long term trim 1 Min 23.43 Max 23.43
short term trim 2 Min 84.37 Max 56.25
Long term trim 2 Min 23.43 Max 23.43

-- those show BIG leak not counted by MAF air rushing in. or MAF Senesor is not reding properly.