Rough idle/Cat

[timtenor]

My 1989 350i refuses to tick over and seems to get worse when the cooling fan kicks in.
From cold it always starts with no problem.
As the engine gets warm it starts to surge as if looking for fuel.
If you give it some fuel it seems to be better until you take your foot off the accelerator and it stalls. It starts up again but will not idle.

I have - replaced the coolant sensor and done the usual, plugs and leads but to no avail.
I cannot find any leaks around the intake manifold/plenium

On a different topic - does anyone know of an aftermarket catalysator for this engine. I am in germany and 3900 cc with no emissions is bankrupting me. The tax alone is almost 1000 Euro per year !!!

thanks for your help

Tim Evans

[broadside]

Not sure about a catalytic convertor for a wedge. One of the reasons that the Griff and Chimaera that followed the wedge were built on different chassis and TVR not continuing with the wedge chassis was the lack of room for cats for TVR to meet the compulsory cat regulations that came in to force in 1992/93. If I remember correctly there may have been cats fitted to wedges exported to the USA but they were all V6 280's and not v8s.

I suppose the only thing stopping you from fitting cats is time and money .....plenty of those and anything is possible!!

As for the rough idle, I think this has been covered before and one of the more knowledgable chaps will be along in a minute to help!!

Nige'

[adam quantrill]

Sounds like it's getting rich when warm - try the Engine Temp Sensor first. See the FAQ articles for loads on this.

What are the rules for emissions then, in the UK they only apply emissions regs to cars made after the rules were brought in.

Adding a cat will add to your CO2 output, are you being charged for CO, or CO2?

[mrzigazaga]

http://pistonheads.com/gassing/topic.asp?h=0&f...

[timtenor]

I've already replaced the temp sensor so the ECU should be getting the correct message that the engine is warm. It didn't make any difference. Just yesterday with careful "tickling" of the accelerator pedal I was able to get the engine to tick over and then when the fan cut in the engine stalled again. I am fairly sure that the problem is electrical and not fuel related. Unfortunately electrics and engine management is not one of my strong points.

Tax in germany is based on cc and the charge is for ever 100cc of displacement.
Cars under 30 years old are now required to display an emissions sticker in the windscreen.
The worst and most expensive catagory is not having a sticker at all (The TVR is in this bracket) followed by red, yellow and green. Some cities will now not allow any vehicle without a green sticker into the city center. Even my mundane 2002 Mondeo diesel is restricted to a yellow sticker. I could upgrade the cat for around 600 euro. My 350i would currently cost 1014 euro a year in tax. Even bringing the emissions down to a Euro 1 (the same as my 1996 Golf TDI would bring the tax down to ca 605 Euro)

If I could find insurance in the UK that would give me year round insurance in Europe the problem would be solved. My MGBGT V8 is insured through Haggerty but they will not insure TVR's later than 1980

[adam quantrill]

Hi Tim,

it sounds like you have a few cars to chose from to drive, so presumably most of them are parked up in the garage from time to time. With UK insurances covering say 30 days at a time for "a european trip" you could probably insure three times with very limited mileage on each insurance for around £100-150 a pop. Then "lay the car up" when you are finished. So that gives you three months driving. UK car tax is £220 now and £50 for an MOT so you might scrape in around £500 all in.

Anyhow back to the engine I would look at the throttle pot next. And the earth straps around the engine bay.

[timtenor]

Thanks Adam.
I am about 600 miles from the coast, so, driving back and forth to comply with insurance, MOT etc is not really an option. I have to join the German TVR club and find out from a member what the best way forward is.

I'm away for a few days now but will try your suggestions when I get back.
Thanks for your help.
More later.

[jon haines]

I had similar issues a couple of years ago and after replacing all the things you have replaced plus airflow meter it was still basically the same, i then tried an ecu and that sorted the problem but by that stage i had spent hundreds and then had my ecu refurbed and the car has never been so good since so if you could borrow an ecu to try i would recommend that.

[rev-erend]

You could try classicline car insurance... they insure my TVR.

[phone]

Another option is to add a short after market catalyst before the centre box and fit a shorter centre box. I fitted a shorter centre box to mine, it was made by JP exhausts and was very reasonable for cost. You would also need to fit the later fuel injection - hotwire and 14CUX. It sure is a lot of work.

Catalist
http://www.johnealesroverv8.co.uk/17.html

Centre Box
http://www.jpexhausts.co.uk/

[Tasmin200]

If you are serious about fitting a cat and your car's running rubbish why not combine the two jobs?

Throw away the old ECU and fit something like an Emerald or Magajolt ECU. That way you get your car running great and mapped to suit the new cat.

Just a thought.

[timtenor]

Arrived home today and car started straight up as always but cut out when engine was warm.
Checked for leaks and also checked for loose plenium scews but everything looks OK.
Took out the plugs to find that they are as black as coal. Obviously the engine is running very rich. Unplugging the (new) temp sensor made no difference. I do not have a 200 ohm resistor has anyone tried improvising with a paper clip?
I am going down the path of thinking that the ECU is damaged or is receiving the wrong information. Could a new temp. sensor be faulty?

[TOPTON]

Unless I've missed reading it, you haven't mentioned the cold start injector. If that is powering up all the time it would certainly give the symptoms you have.
Unplug it and try. It will run nomally without it ever needing to be re connected, unless you live in a -20 temp area

[timtenor]

I'll unplug the cold start injector tomorrow.
Thanks
More later.

[honestjohntoo]

timtenor said:

I've already replaced the temp sensor so the ECU should be getting the correct message that the engine is warm. It didn't make any difference.

timtenor said:

Unplugging the (new) temp sensor made no difference.

Could be faulty but because the fault existed with the original sensor too, more likely to be the wiring between the sensor and the ECU and the local earth tag.

Suggest you repeat testing using the recommended procedure.

CTS Testing

Conditions as follows: Engine HOT, ECU multiplug disconnected as in A: Ignition OFF: Measure coolant temperature with thermal probe: Connect an ohmmeter as shown in B below and take a single reading. Compare it to the resistance/temperature profile below.

Allow the engine to cool and take further readings. If the measurements match the profile within (say) 10-15%, the CTS and its connections are OK.



TEMP.......OHMS........TEMP........OHMS

-10°C...9100-9300....60°C.......500-700

0°C.......5700-5900....80°C.......300-400

20°C.....2400-2600....100°C....150-200

40°C.....1100-1300

If the readings are clearly wrong, remove the sensor for a controlled test using a pan of water and thermometer.

Suspend the sensor in the water and bring to the boil. Compare resistance readings to the profile. Variations of (say) 10-15% are not critical but if they are obviously way off or there is a clear intermittant or distorted result then consider the test failed. Obtain a replacement unit, check it as above to verify OK, fit it into the manifold and reconnect to the Efi circuit. Reconnect the ohmmeter as in B and repeat the measurement between the ECU pin 13 and earth. If this still incorrect there is a wiring problem so check the black/slate wire (BS) and black/white wire (BW) and their connections paying particular attention to the earth stud at the rear of the engine.

Clicky for Loads More here

[timtenor]

I unplugged the cold start injector today and the engine started up without problem and was much smoother whilst going through the warming up phase. When the fan came in the engine did not stall - so, already quite an improvement.

When you give fuel and quickly release the throttle the engine will not return to idle but instead will stall.

I have also found rubber tubing coming from the plenium that is without a jubilee clip. Could be that this is sucking air?

Will investigate this further and do the tests on the temp sensor to try and make further improvements. Must first buy an electrical tester as I am going into unchartered waters here. Most of my experience is with mechanical systems not electrical - MGB's, TR's and the like. Thanks for all the advice and help.

[timtenor]

I'm waiting for an electrical tester to arrive that I've ordered from ebay but in the meantime - I've located the ecu in passenger footwell. Largish aluminum box with no markings - no name, serial number, nothing. Has two rows of pins some of which are blank. Connection looks sound. Above it is another small black box with heat fins and a six pin connector. Don't know what this is but the connection looks good. You can unplug it and the engine will still start. The only marking is "Lucas 12V" I've removed the connection to the temp sensor and bridged the terminals with a 200 Ohm resistor. No change - stinks of fuel, plugs are black, engine runs terrible.
I've taken the temp sensor out of the equation but the ECU or some part of the electrics is not getting the message the we need less fuel.
ECU broken? Don't really want to go this route without knowing for sure. £ signs are flashing before my eyes.... Hmmm

[timtenor]

Maybe it's worth mentioning that this car has been dry stored since 2009. I've only driven it ca 1000 miles and it never ran well. In 2009 I hit a concrete post and put the car to rest until I had time to deal with it. The bumper has been repaired and my goal is to get it back on the road. Around 2004 the car had a body off rebuild and the total mileage is still under 44000 - chassis is excellent.