Any ideas on my jerking?

[kentishS2]

Now the engine has been rebuilt and the heads skimmed and ports polished and it's been back together and on the road about 3 weeks during which time it has been running fine but yesterday it decided to start playing up. 1990 2.9 S2 by the way!

I now experience a rather bad hesitation and very bad jerking as I start to accelerate. If I press on the gas more it goes away. If I back off it also goes away.

I noticed some cracks in the servo hose so I'm changing that but I don't think it's leaking as I gave it a quick pressure test after I took it off and it was OK.

I've recently replaced the TPS and the idle control valve and a temperature sensor for the Efi and it ran fine with these new items installed. Then had the engine rebuild and it has been fine for 3 weeks, until now.

Any other ideas on what may be causing this?

Thanking you in advance....

[kentishS2]

Someone has usually been there before me, I can't really afford to go through all the expensive diagnostic testing and replacing of everything ..again.

No thoughts at all anyone on what this could be?

[shmern]

kentishS2 said:

Someone has usually been there before me, I can't really afford to go through all the expensive diagnostic testing and replacing of everything ..again. No thoughts at all anyone on what this could be?

I know you have replaced the TPS recently, but that again would be the first port of call, just disconnect it and drive again, if it drive ok then TPS it is.

Mine was replaced about 2 months ago, and has died again

So I need a new one

Shmern

[shnozz]

claires S had similar symptoms recently and unplugging the TP made no difference. Turned out to be the coolant sensor but thats no help

Its easy to point to the TP as they are so common to fail and I have heard of 3 week old TPs being crap. Leebee had 3 in 3 months

Air flow meter?

[kentishS2]

Thanks guys,

I guess it could be TP again, I've had new idle valve and coolant sensor and one new air flow meter.

Strange that it is only at a certain engine load (just as you start to pull). Power on and it stops and lift off and it stops jerking too.

I also noticed that the rotor arm is a bit knackered which I'll replace but not likely to be that. I had a similar problem a few months ago and it went but only after I got fed up and let the garage sort it at a cost of £380.

[shnozz]

ah sorry - didnt realise you had a new air flow meter already.

are there any S owners local to you that could swap over the TP before you head off to ford demanding a new one in exchange? (PS - cerbera TPs are cheaper and I know leebee, and I think Johno, went down this route when they were frying the TP time and time again)

[shnozz]

if the rotor arm, dizzy cap and plugs need changing anyway I guess its not a bad time...

>> Edited by shnozz on Wednesday 21st July 14:56

[shmern]

kentishS2 said:

Thanks guys, Strange that it is only at a certain engine load (just as you start to pull). Power on and it stops and lift off and it stops jerking too.

Thats how my TPS tend to show the failure, It's only on certain throttle positions the TPS must give dodgy readings.

I cracked open my old one, and it really looks like a basic Variable POT.

Shmern

>> Edited by shmern on Wednesday 21st July 15:03

[Podie]

Could be running too lean...

[RichardR]

How about the TP connector?

I had a similar problem with mine which went away when I disconnected the TP. Fitted a new one and the problem came back, so my next port of call will be to replace the connector with a new one with the gold plated connections - about £10 from a Ford dealer.

[kentishS2]

RichardR said:

How about the TP connector? I had a similar problem with mine which went away when I disconnected the TP. Fitted a new one and the problem came back, so my next port of call will be to replace the connector with a new one with the gold plated connections - about £10 from a Ford dealer.

Thanks to all.

Looks like most of you suspect the TP, I didn't think it could be after such little time and few miles since fitting the new one but it would appear that they are not know for their long life!

If anyone has part numbers for the gold plated connectors and the Cerbie TP I'd really appreciate it as my local Ford dealer can usually only tell me what I need if I give them a chassis number!

Also, my cap is a grey Motorcraft (Ford) one but was not listed as the one for a circa 1990 Granny and there are no part numbers on it.

I have in the past had a Ford (many years ago) and a numpty previous owner fitted the wrong dizzy cap but it was a close fit and the car still ran (poorly) but I thought it worth checking that I had all the right sparky bits fitted. I noticed my coil looks very old, could that have a similar effect?

>> Edited by kentishS2 on Wednesday 21st July 16:02

[shnozz]

yep, knackered coil can also have that effect.

I have a spare gold TP connector in the garage actually that we bought at the same time as a new TP. Will see if Claire wants it as back up, if not may be able to save you a trip to the local Ford dealer.

[Podie]

kentishS2 said:

Any ideas on my jerking?

Yeah.. don't do it too much.. it'll make you go blind...

[kentishS2]

Podie said:

kentishS2 said: Any ideas on my jerking? Yeah.. don't do it too much.. it'll make you go blind...

Ohh behave!

[V8Smith]

Podie said:

kentishS2 said: Any ideas on my jerking? Yeah.. don't do it too much.. it'll make you go blind...

He did post a VW Passat question on the 'S' Forum..............mmmmmmmmmmm

[s1.5f]

kentishS2 said:

Now the engine has been rebuilt and the heads skimmed and ports polished

Kevin

Sorry to off-topic but how have you found the engine/performance since you had your 'eds looked at?

Simon

[kentishS2]

s1.5f said:

kentishS2 said: Now the engine has been rebuilt and the heads skimmed and ports polished Kevin Sorry to off-topic but how have you found the engine/performance since you had your 'eds looked at? Simon

Hi Simon,

Difficult to say as it has this new fault but without going too mad after getting the car home after the rebuild it was much more responsive and the acceleration was better and I did notice that I could get to a higher MPH with the roof down.

I was pleased but it was expensive at £840!

KS2

shnozz said:

yep, knackered coil can also have that effect. I have a spare gold TP connector in the garage actually that we bought at the same time as a new TP. Will see if Claire wants it as back up, if not may be able to save you a trip to the local Ford dealer.

Thanks Phil, that's kind of you. Yep, I'll have if you wont need them and get a cheque off to you.

I'll pop a new coil on too ...here I go again, think I'll buy some Ford shares!

>> Edited by kentishS2 on Thursday 22 July 09:32

[NickP_S2]

My S2 has the same symptoms when its running cold. Seems do disappear once its warmed up a bit.

[Podie]

NickP_S2 said:

My S2 has the same symptoms when its running cold. Seems do disappear once its warmed up a bit.

Well given that everyone ignored it first time round… I'll try again… it's probably running a bit lean...

[kentishS2]

Podie said:

NickP_S2 said: My S2 has the same symptoms when its running cold. Seems do disappear once its warmed up a bit. Well given that everyone ignored it first time round… I'll try again… it's probably running a bit lean...

Who said that!

Ah sorry Podie, yes that's a good point.

I think my problem is something failing as it wasn't like it and it's just been set up on the machine after the engine rebuild.

Can the mixture be increased, is there an adjustment?