Throttle Body

[Teflon]

Member Saga lout kindly gifted me some refurbed throttle body parts that he had spare, and I decided to make good use of them.

I had a spare throttle body in the shed which I knew was in working order as it had been on the car when I first bought her, all those years ago. Anyhow, I ordered a new gasket set from Rimmers, and set about cleaning the unit, followed by masking, priming, and painting. It weas then re-assembled using new gaskets and "O" ring, plus the linkage parts from Saga Lout.

Really pleased how it came out:



Fitted it to the '75, and it looks great in the engine bay. Sadly though, it doesn't work . The car starts fine, and idles nicely, though perhaps a little fast. Wasn't too concerned at this as the engine was stone cold, however as soon as the pedal is pressed, the revs rise, and rise, and rise, - you get the idea.

The throttle does not appear to be physically sticking - everything falls back in place as it should, except the revs! I'm thinking an air leak perhaps, but can't imagine where from . Idle Air Control Valve perhaps? I really have no clue.

I have replaced the old throttle body, and everything is again working as it should, but I would love to have the refurbed unit working properly - any ideas folks?

Cliff

[KWIL]

Cliff,

If it is the Idle Valve, just block the supplementary air inlet tube, either directly or in the air filter housing if that is all set up, revs drop? you will know its the Idle valve, if they do not, you have another leak

K

[Teflon]

Thanks Ken, I'l give that a go tomorrow

Cliff

[Teflon]

So, this morning I refitted my re-furbed throttle body, but only after taking the idle control valve off, and giving it another quick clean.

Result was a little better, but still no go. From cold, things seemed almost normal (revs a little high, but not too bad). Once the engine had warmed, she ticked over quite nicely, but when revved, the engine stayed at the higher revs . An improvement over yesterday, but still unusable.

With the engine revving away happily at around 2k, I did as suggested and blocked off the top inlet (brass bit). This caused the revs to instantly fall and would have stopped the engine. Unblocking it before the engine stopped, and she idled away nicely until revved up again.

In view of the above, I'm presuming a new idle control valve is required, does this sound right?

Obviously, the simplest solution would be to swap over the valve from the throttle body that's currently on the car. Thing is though, I'm loath to try this in case I stuff up the working throttle body and end up with an undriveable car . She's been in that state long enough this year already!

Cliff

[KWIL]

Cliff,

Sounds correct to me, you have apparently isolated the problem. I was going to suggest swapping the Valve body. I cannot really see how doing that could leave you as you fear, but I suppose there is a chance. What puzzles me is that left on warm up. it settles down to tickover, so the valve is closing as it should. There is the 5 throttle movement reset procedure, when the engine has warmed to tickover, switch off, switch on without starting, accelerator 5 depressions, switch off, then restart, might work.

Ken

[Teflon]

Cheers Ken.

I've bitten the bullet and ordered a new valve from Rimmers, so should have it all sorted by the weekend I hope .

I'll report back once it arrives. Thanks for the advice

Cliff

[janker]

Originally Posted by Teflon

Cheers Ken.

I've bitten the bullet and ordered a new valve from Rimmers, so should have it all sorted by the weekend I hope .

I'll report back once it arrives. Thanks for the advice

Cliff

Will be interesting to see how you go on ive had this problem for ages and tried a secondhand throttle body,New seals etc and new kit for idle control valve,no leaks but same problem as yourself,I really didnt want spend that much for a new one from rimmers and could have same issue so im very interested to see your result.

cheers julian

[Teflon]

Originally Posted by janker

Will be interesting to see how you go on ive had this problem for ages and tried a secondhand throttle body,New seals etc and new kit for idle control valve,no leaks but same problem as yourself,I really didnt want spend that much for a new one from rimmers and could have same issue so im very interested to see your result.

cheers julian

Well I've got the new part from Rimmers (only ordered it yesterday afternoon!), and have finished priming and painting it. I'll have it fitted tomorrow morning and will let you know how it goes.

Hope it works, as I can't return it to Rimmers now I've painted it .

Cliff

[Teflon]

Fitted the refurbed throttle body this morning, complete with new idle control valve. A massive improvement, but still not 100% right.

She ticked over quite nicely and didn't misbehave when revved, BUT, when I tried to drive off, as I took my foot off the throttle pedal, the revs dropped very low (almost stopping the engine), then rose to a very fast tick over. It then repeated this pattern a few times before settling back down to tick over. I found it would do this every time I revved and released the throttle pedal (even though it had seemed fine while sat on the drive).

The car was driveable, and it may well have settled in after a short drive, but I didn't consider it particularly safe, so the old throttle body is back on for now.

A real shame, as it looks mint and is working around 98% right

I suspect the new throttle body could be made to work properly by someone with the right skills, so my current plan is to leave it until I have access to someone with T4. I'm looking to get new discs fitted shortly, so will probably add it to that task.

Worth adding, I tried the throttle re-set procedure with no improvement.

Cliff

[Odd Job]

That really is a shame it's not working right, it looks fantastic!
Always nice to see engine bay components with a dash of colour on them!

Best of luck and hope you get it sorted out soon.