Airflow meters and warm-up problems

[J666GRF]

Since buying my S3C in December its had a warm-up problem. It starts o.k., but then dies if I stop within 15 minutes. The engine is also lumpy and erratic on tickover and rarely reaches operating temperature [yes its had a new thermostat!]. I have mentioned this before on PH and consequently bought a new warm-up sensor Ford part no. 6810428. This alleviated the problem but did not cure it. The car has since spent lots of time at 2 local garages, a Ford main dealer, and a non-franchised specialist and so has cost me an embarassing amount. Is it cured? Is it b---er! Its definitely temperature related because it was barely noticeable during that recent hot spell but its now back to its usual irritating self.
At Tatton Park classic show, I noticed that S2s & S3s with the 2.9 engine all had air-flow meters. Mine is an S3C which has been de-catted and does not have air-flow meters. The question is should it have? [there appears to be wiring for them] I have already asked 2 TVR main agents who confounded me by giving different answers! This is my daily drive and its driving me nuts! I am now well and truly spent-up too!
Anyone out there got any thoughts or inspiration which won't cost me my remaining arm and leg?

[Colin Blues2]

Hi there

There have been a few posts about air flow meters on de-catted cars previously. I think the concensus was that they weren't needed as the lambda sensor compensated for them. However it could be my memory playing tricks, have a quick search on cats.

If it's temperature related have you checked the idle regulator on the front of the plenum chamber is working? You can remove and clean them cheaply enough (get a new gasket though). Also I had issues with the wiring for the idle regulator and throttle pot where it all joins together behind the coil. A dry solder joint was causing it so I re made the joint. Since then things have been much improved.

Colin

[Roy C]

No, the catlysed 2.9 does not have airflow meters.

They have a MAP sensor (a little black plasic box bolted to the bulkhead with wires coming out of the bottom and a tube from the inlet manifold) to measure air input.

[andyf007]

Three parts spring to mind.

1. Faulty Coolant Temperature Sensor (has been known to affect the running temperature and can convince the ECU that the car is hot when it's not)

2. Faulty MAP Sensor (incorrect air pressure readings will affect the fuelling)

3. Faulty Lambda Sensor (was this dealt with correctly when the car was de-catted?)

Andy

[NicBowman]

My S3 ran poorly on startup, but okay at temperature. The problem appears to have been the throttle sensor. Don't ask me why or how? It now runs fine when cold. They are only £38 and changed in 3 minutes.

Nic

[hrjs]

I had a similar problem. They took virtually the whole car to pieces, and eventually discovered that there was no fuse in the lambda sensor.

[woody]

hrjs said:

I had a similar problem. They took virtually the whole car to pieces, and eventually discovered that there was no fuse in the lambda sensor.

Wheres the fuse in the lambda sensor? (thought they were a sealed unit type?)

Chris

[hrjs]

No idea. That's what they said, though, and the car's much better now. Is it total rubbish? Seems unlikely they'd make it up...

[J666GRF]

Many thanks to everyone who responded.
In particular RoyC you have saved me another expensive blind alley concerning airflow meters, I will check out the MAP sensor. andyf007 I have already replaced the coolant sensor which is the Ford part number I mentioned, and 1 of its 2 lambda sensors when an exhaust manifold was replaced. I was not aware that these were fused, and as the car was de-catted long before I bought it I have no idea as to whether this was done correctly. Someone else has mentioned a throttle potentionmeter although my local Ford agent quoted £59 + VAT. Give me a clear weekend and watch this space.

[trevytrev]

This sounds very much like the problems I used to have with my S3C. First of all I can confirm that they do not have air flow sensors. The S3C's use lambda sensors, a long with a couple of other sensors which the ECU uses to control the fuel and air mixture of the car. The problem being (from what Paul told me at Austec) is that the ecu for the S3c was designed for a different car and TVR kind of made it work with the engine for instance the ECU only accepts one lambda sensor so TVR spliced the wires from both the lambda sensors together to fool it !!.

I spent nearly six months trying to get my S to run right especially when it was cold (have a look at my profile to see the posts I made !). Mine like yours never seems to get up to temperature unless I am sat in a good 10-15 minute traffic jam or the weather is really hot.

The answer for mine was to get it chipped and set up on a rolling road. have a look at for more info..

www.pistonheads.com/tvr/s/default.asp?storyId=7562

The difference to the car is totally amazing whether it is running hot or cold. Unfortunately it is not a cheap solution but I would say if you book your car in to Austec then they will find out what the problem with it is.

One other cheap thing that I found really useful when trying to resolve the problems with mine was to buy a gunson fault code reader (get them from halfords about £16 you need the ford 3pin one, part number 4152). This will plug straight into a lead off the ecu and allow you to run a full test on all the engines sensors etc and may tell you exactly what the problem is.

Trev