Powers Performance throttle body gaskets

[Robertjp]

For a while now i have been noticing rough running at idle from cold (almost like a very slight misfire), but that quickly goes after a few minutes. I put it down to TADTS...but it just didn’t feel right.

A niggle more than anything but its been bugging me – it was noticed during my 6k service but it quickly disappeared so nothing more was thought of it – there were a few other minor things that could have been causing the problem and they were resolved, so quite rightly we thought the problem had gone.

Anyway, about 400 miles on and this slight misfire was back....now i already have roller bearing throttle bodies, and with such a recent service ii hadnt suspected a problem here – but i did check them again recently and they were out of sync!!

A bit confused, i reset them all AGAIN, and next start up – car was perfect. Thought it was problem solved...until the bloody thing started again less than 100 miles later!!!

Getting frustrated at this point and suspecting the throttle bodies were leaking in some way – i purchased a set of Power’s Performance Throttle body gaskets. A lot of money but i decided to bite the bullet and take an educated guess that air leakage under the throttle body flanges was the problem.

Fitted them on Saturday...the car decided to fight me all the way while installing the job took about 5 hours, but at least an hour of that was spent looking for a bolts...word of advice, get a telescopic magnet with torch and a light coloured sheet for under the car BEFORE starting the job...believe me you will need it several times. Oh, and some thick gloves to prevent getting burned if you have run your car first .

When i inspected the flanges on the throttle bodies once they were removed, i was very reassured to find oily residue across most of the mating faces...indicating that they were in no way air tight, and yet they had previously been sealed with hylomar. After bolting it all back together, looking for more bolts and several adjuster arm springs that have a mind of their own....a throttle balance and throttle pot reset...initial signs were that they have made an incredible difference. Idle is smoother than it has EVER been, pick up is silky smooth, its quieter and just feels so much better.

I have only had a quick spin round the block with them fitted, so weather permitting i will be in the car tomorrow to give some proper feedback...just hope the start from stone cold is without a hint of a problem!!!

[Robertjp]

pete it was your threads that made me think of the leakage, but i decided to go for the gaskets in case they ever have to come off again and its not me that puts it back together
anyway, used the car for work today and early signs are its been fantastic, its an absolute pleasure to sit at idle now and then pick up is so smooth. Still early days but so far Im v pleased i spent the money on these

[Robertjp]

s6boy said:

Any of these symptoms similar to yours Rob - Poor/non starting from very cold (below 10 degrees), uneven idle and PITA to drive until a little temperature in the engine, spitting back from one or more cylinders when blipped cold?

Cheers

Pretty typical of a poor AFR IMHO...i would check your throttle bodies with a syncrometer and reset them, then do it again in say 500 miles - if they have changed its a good indication.

If its spitting it suggests its running too lean - i.e. too much air...i had the same when trying my 'first' throttle body balance and was pulling way too much air. Its needs to be round the 6-8kg/min mark (or whatever the units on the syncrometer are )

[Robertjp]

s6boy said:

Thanks, I was coming to the same conclusion before reading your thread good to have another opinion. However it's the fact that when hot the engine behaves perfectly which has been puzzling me. Now thinking a leak is being affected by a bit of thermal expansion when up to temperature.

Thats another indicator its the flanges IMO...thats why i was getting the rough 'cold' start - i think as soon as they had some warmth they were closing up and reducing the leakage...