Hesitation/shunting help.

[natben]

Hi Guys, can anyone help?

Recently my car has started to hesitate /shunt/stutter when driving between 2,000-3,000 rpm.
I had it hooked up at to the laptop at my nearest TVR service centre and they adjusted the tickover as it was stalling and is now ticking over ok ,cold and hot. They didn't notice anything unusual and I got it back but it is still shunting/stuttering.

So any ideas.
It isn't a misfire as it would have shown up on the diagnostic software at the garage so I take it that rules out plugs/leads/coil pack??.

Engine mounts?? there is a bit of vibration from the engine area when I am reversing into my garage. How do you know engine mounts need changed?.

Throttle bodies worn? Costly at around £1k to change and wouldn't like to spend this cash if it isn't the fault having not long spent almost £8k on a rebuild.

So can anyone advise me what I can check. I am a novice mechanic but I'll give it a go!
Thanks in advance
George

[natben]

Hi yes they had it hooked up to the software and ajusted the throttle bodies to allow them to ajust the idol and they did say they were quiet a bit out, It ticks over ok now but still has the hesitation/shunting.

I'm thinking engine mounts but wouldn't that be more noticable on sharp accelaration?
Sensor came loose somewhare?
Throttle cable sticking but it is only really noticable between 2-3000k rpm especialy in a higher gear wouldn't it be right accross the rpm range?

Or throttle body bushes (ouch £1k, upgraded bushes only available from Racing Green I think).

Anyone changed bushes, what were the symptoms?

George

[natben]

Thanks for that Fad, worth checking, But what does a throttle linkage look like?, Can anyone post a picture for me? .Is it the link between each throttle body?. I will remove the airbox tonight and have a look.
George

[natben]

I removed the air box and checked the HT leads were all pressed home into the coil pack, seemed OK
I sprayed some WD40 on the linkages between the throttle bodies.
I started the engine and let it idol up to temperature, when I pressed down on the throttle and held it at about 2000-2500rpm throttle 3&4 spat some flames very slightly where as all the other throttles were ok. Is this anything to suggest it's the culprit/misfire?
Anyone know what the purpose is of the black pipe that runs below the throttle bodies and connects at the far right hand side.

[natben]

Thanks for the replies guys, I think I will change the coil pack as a first step as the leads were changed last year so in theory should still be ok.
If this doesn't cure it then I will get new HT leads, but wouldn't any of these items shown up as faulty when the garage had it connected to the software.
George

[natben]

SORTED

Massive, massive thanks to Dom at TVR Power, one quick chat with him and he had the issue diagnosed!! Throttle pots!!! he sent me them up (2) I fitted them, then using the software and the help of local TVR owner who brought his old lap top to allow the software to run, the addaptives were re set and all is well again. The car idols perfectly and is silky smooth.

So no need to spend £1k on new throttle bodies! thank feck!!.

Thanks Dom.

[natben]

Robertjp said:

natben said:

SORTED

Massive, massive thanks to Dom at TVR Power, one quick chat with him and he had the issue diagnosed!! Throttle pots!!! he sent me them up (2) I fitted them, then using the software and the help of local TVR owner who brought his old lap top to allow the software to run, the addaptives were re set and all is well again. The car idols perfectly and is silky smooth.

So no need to spend £1k on new throttle bodies! thank feck!!.

Thanks Dom.

Glad you are sorted. Word of caution though if the throttle bodies were worn thay could have contributed to your throttle pots failing, and if this is the case they could fail quicker this time.

...and wh
ere did you get the idea it was £1k to fix tb's??!

The garage that set up my idol. When I phoned them back up and said there was no improvement with the hesitation but the idol was now ok they said the next step would be new throttle bodies and it would be about £1,000 fitted.
Thank goodness Dom got in touch and diagnosed the problem instantly over the phone. I can't thank him enough and Grant who came over and showed me how to use the software.
I will keep an eye on the throttle bodies over the next few months and now I have the software working I monitor the set up more accurately.
George

[natben]

Hi Sagi,
I did balance the throttle bodys with a syncrometer and they were all level, but at IDOL not as you suggested at 2/3000rpm. I have also tonight replaced the HT leads but unfortunatley there is still a shunting at low rpm, I thought it was solved but it is still there not as bad but still noticable I can feel it through the accelerator pedal and it is not the smooth drive that it once was.
I am away from home now until the end of the Sept and as the Tax is up on the 1st October I think I will SORN it for the winter and revisit it in the spring.
Thanks for taking the time to comment.

George

[natben]

I started the Cerb today after 3 months lying idol due to work and it was running very very rough. I went around the block for a quick drive and it was hopeless, backfiring and very very lumpy. I made it back to the house where I left the car ticking over on the drive while I got the lap top connected to the ECU and as soon as I did this the car got very lumpy on tick over and eventually stalled. It will not re-start.

The car has been in a dry garage and connected to a battery charger over the winter. My fuel was very low and I thought this may have been the problem so I filled up a Jerry can with V -power and poured it in but the car still refuses to start.

Dom kindly sent me some throttle pots that I thought had initially helped but hasn't, I also replaced the HT leads, my second set within a year but still no real difference. should I go for a new coil pack now, but I don't really want to just go replacing things that wont sort the issue as I spent virtually £9k on it last year and I can't spend much on it at this time.

Any pointers to try and get it started first would be a help, then I can see about getting this rough running sorted once and for all.

Any ideas guys.

George

This is how the software looked just after the car stalled on the drive

Edited by natben on Saturday 16th February 18:34

[natben]

Well I managed to get the car started 3rd or 4th time this morning and had to hold the revs above 2000rpm to prevent it stalling for 10sec or so but then it settled down and tickover was back to being stable around 850rpm. It looks like the small amount of fuel sitting in the tank may have got contaminated (thanks Shep101 for your reply above)and then running out of fuel on the drive had prevented the car re starting.
I went for a short run this morning and it is still a bit lumpy around 2000-2500rpm but the fact it has sat still since mid Sept may have something to do with that but I will get it to TVR Power soon for a service and get them to look at the hesitation around 2000rpm.

I have attached a picture from the diagnostic screen below, if anyone spots anything out the ordinary please let me know.

Edited by natben on Sunday 17th February 13:00

[natben]

Thanks for the reply Shep,
I think I will take your advise and change the fuel filter as it is very likley that some crap may have got into the filter from the tank and I will order a synchroniser up and have a go at balancing the throttle bodies.
I have to drive 350 miles to TVR Power for the service so probably worth trying to get the engine as well set up as I can before embarking on that trip.

I may be back for advice on how to balance the throttles!!

Thanks for taking the time to reply.

George

[natben]

Still no joy..........

Throttles are all balanced ok, but still the car is shunting badly around 2000rpm. It drives ok on the motorway at cruising speeds of 70-80Mph but in slow traffic around 20-30 mph it is a bh!.

I am thinking I will fit the TVR Power TB gaskets to see if that helps, is this something I could do being a novice with the spanners?

Has anyone fitted them that could advise?

Failing that I will have to get the credit card out and take it somewhere that can set it up properly......aaggghhhh.

George

[natben]

m4tti said:

Can you replicate the hesitation whilst stationary or only whilst driving?

No I can,t replicate it whilst stationary, It is most noticeable driving slowly at between 20-50 mph.

[natben]

paulvx220T said:

I have had the throttle bodies off a few times, once to fit the gaskets and they a do make a hell of a difference. No more backfiring in the throttle bodies. A tip is to remove all the throttle bodies as one while still attached to the fuel rail. It takes a bit of rocking back and fore to loosen them where they are located on the dowels but it’s relatively easy and on the occasions I have done it this way I have not disturbed the throttle settings when I have checked with the syncrometer.

Paul

Paul thanks for your advise, the throttle body's are balanced even at about 6, but I do get some backfire through throttle body 3 when I increase revs with the air box off. If the body's are drawing in air would they stay balanced at say 6 across all of them or would one show up wildly out?
I would like to fit the gaskets myself as I have a family holiday coming up and I have just spent on a12k service so I can do without sending the car down south and spending another £700 at this time.

But can I do it without making things worse! I have removed the fuel rail before when I had it powder coated but this feels like a far bigger job.

Edited by natben on Monday 22 April 22:23

[natben]

Robertjp said:

Its a piece of cake to fit the gaskets, a little time consuming but very easy.

The slightly tricky bit is refitting the throttle bodies, you will need to set the clearances from scratch. They need to look almost closed.

Then you are looking at 6-9 kg/min through the syncrometer.

Thanks for your continued advise on this subject Robert, as you have probably relished I am very much learning as I go, having had very little contact with engines previously.
I would like to do this as a last attempt to fix before I send it down south at more expense!

Just need to pluck up the courage, the fact you guys have done it may just give me the confidence to give it a go.

George

[natben]

paulvx220T said:

I have had the throttle bodies off a few times, once to fit the gaskets and they a do make a hell of a difference. No more backfiring in the throttle bodies. A tip is to remove all the throttle bodies as one while still attached to the fuel rail. It takes a bit of rocking back and fore to loosen them where they are located on the dowels but it’s relatively easy and on the occasions I have done it this way I have not disturbed the throttle settings when I have checked with the syncrometer.

Paul

Paul, what type of Hex/Allan key did you use to remove the throttle body's, I have plenty of standard size keys but none of the 6mm ones will allow me enough leverage to get the bolts out and getting to the bolts on throttle body six looks like an impossibility. Is there more room in a Tuscan between number six and the bulkhead. I would like to fit the gaskets my self as it would help my knowlage and understanding of the car and save a few quid after spending on road tax, tyres, 12k service and MOT in the last month.

I would ideally like to do as you did and remove them in one go while attached to the fuel rail.

George.