Occasional starting problems and poor running / misfiring for first few miles

[Caterham Kid]

I have a K series 1.8 140bhp. About a month or so ago I started up the car and drove off to find the car running as though it was only running on 3 cylinders and it was misfiring. It wouldn’t accelerate properly and was difficult to drive. It was very jumpy as though the fourth cylinder was intermittently firing. It cleared after a mile or 2 and all was ok. I went to the Surrey Sevens meet this Tuesday and exactly the same thing happened only it took longer to clear and it was more difficult to start. When I left to go home it happened again. I stopped for fuel close to home and when I got back in the car it was difficult to start and happened again and remained for the 3 miles to get home.

 

Last night I did a reset of the Throttle Position Sensor (TPS) as on a couple of occasions I had to blip the throttle to get the car started. I understand from Redline that this also resets the IACV. I did note though that I didn’t hear any sounds when I did the reset which I was told by Redline I would as the IACV resets. I also checked that the HT leads were connected properly and that the connections on the injectors were ok. I also checked that the alternator was charging as it should (it was). After resetting the TPS the car started ok. Today I took the car to work which is a 150 mile round trip. It started ok first thing and was running fine. I stopped about half way to work to pick up a colleague. When we set off it was difficult to start again, but it did, and it ran ok. When we left work this evening it started ok and ran fine. I dropped my colleague off and then when I went to leave it wouldn’t start very easily and it took at least 5 miles or so to clear. When I got home I switched off, left it a couple of minutes and tried to start it. Sure enough it wouldn’t start. I disconnected the Lambda sensor but that made no difference. Tomorrow I intend to get some new spark plugs and will hopefully change those by the end of the weekend. If that doesn’t do it my next suspect is the HT leads. They are the type with the coil packs bolted to the top of the head. After that I have no idea what to check.

 

Has anyone got any ideas what to investigate next?

 

Sorry for the long post but if the change of spark plugs doesn’t do it I will probably have to send it in to Redline. I would probably have to get them to do the HT leads anyway as I would more than likely have to get them from Redline and I am not sure I would know how to change them. It is going to have to go in anyway as I picked up a stone chip in the windscreen today!

 

Once again sorry about the lengthy ramble!

 

 

[Caterham Kid]

New spark plugs hasn't fixed it. ☹️

 

I have run out of ideas now.

 

No one got any additional thoughts?

 

 

[Steve-B]

CK, see my post today on TPS, what you're reporting is almost word for word in your 1st paragraph. So I'd replaced plugs, disconnect + on my battery, did the ECU reset game and it all seemed OK.

 

Now it's SKippy the Kangaroo in 1st, 2nd, 3rd, especially under 30Mph, or at 70Mph in 5th.

 

My TPS is 12 years old, I am seriously suspecting it's that as I've never (knowingly) put dodgy petrol in.

 

My only other suspicion is could the fuel pump be marginal and causing this? That's just occurred to me as NOTHING else on our car has been changed for years.

[Caterham Kid]

Steve

 

My problem sounds very similar. The only difference is that after a few miles the car is absolutely fine. Then you wouldn't know there is a problem. It is clear throughout the rev range.

 

How do you do the ECU reset... or is that the same as the TPS/IACV reset?

 

What concerns me is I can hear a slight hissing noise when it happens. Or I might just be being paranoid.

 

Also occasionally I used to hear a noise like a valve operating when I turned on the ignition. I don't believe I have heard that for a while and not sure if that is related.

 

If I don't find the issue in the next couple of days I will have to book it in for investigation.

 

 

[Steve-B]

CK, the reset I probably used wrong name, my bad. It's the disarm-key- on-don't start but push throttle wide open - and the turn off procedure.

 

Are you not hearing your fuel pump whir before you start? That's the only sound I'm aware it kind of matching our description.

 

If you want to wait a week, as soon as someone confirms the part number I'll order one for mine and let you know how it goes..l

[Caterham Kid]

Steve

 

No I don't seem to be able to hear the whir when I turn on the ignition. I was led to believe that was the IACV but it makes sense that it is the fuel pump.

 

I have done the reset you describe, except pushing the throttle pedal to fully open and back 5 times then ignition off. It doesn't seem to help.

 

Not sure why it seems to be worse when the engine is hot and then I try to restart.

 

Have you narrowed yours down to the fuel pump? I will be interested to hear if you get yours resolved.

 

I think I will book it in as there seems to be so many different things it could be. Although I have fairly good theoretical knowledge I am not sure I have enough practical knowledge without help to sort this.

 

 

[Caterham Kid]

I spoke to Redline again today. Will book it in but can't get it there until 19th August. Until then they have told me to investigate the ECU temperature sensor and the IACV. Apparently if it was the fuel pump it probably wouldn't run at all. From my research I am beginning to suspect the IACV as I can't here the noise when I switch on the ignition. Can anyone tell me where I can locate the IACV exactly?

 

 

 

Edited by - Caterham Kid on 22 Jul 2013 17:02:19

[CharlesElliott]

Look here on the SELOC Wiki.

[Caterham Kid]

 

Excellent! Thanks very much.

 

Hopefully I will get to investigate it this evening.

 

[Caterham Kid]

I see the reset procedure for the S2 (which I think is what I have) is different than for the S1 and I have been doing that (the throttle pedal thing).

 

 

[Caterham Kid]

Well... for now the problem seems to have feen fixed. Although I am not yet 100% confident it has been cured but the next couple of weeks should confirm that.

 

From the link very kindly provided by CharlesElliott above I noted that there are 2 different ways of resettting the IACV depending on whether it is the EU2 (S1) or EU3 (s2) as follows:

 

"Resetting" the iacv

 

S1 (Stepper) The IAC Valve postition maybe reset by switching the ignition on disabling the imobiliser and pressing the throttle fully and slowly 5 times, it may also be reset with the Lotus check tool. This is detailed in section EMN page 14 of the service manual.

 

S2 (PWM) The S2 ECU cant measure where the IACV is so has to count the drive pulses it sends and remember the poistion, then tries to return to a datum every ignition on/off. If it loses track e.g. battery disconnected the ignition needs to be switched on to position 2 and off several times to run the valve back to the datum.

 

I had been using the method for the EU2 which is the one generally known about and posted. However I am fairly certain (nearly 100% sure!) I have the EU3 so I tried that method and so far the problem seems to have dissapeared. I have only given it a couple of runs and tried a number of restarts. So far no problems.

 

Keeping my fingers crossed!!

 

Thanks for all the help and advice

 

I may be back for more if in fact it hasn't been cured!

 

[John Vine]

However I am fairly certain (nearly 100% sure!) I have the EU3

I think you said your car has coil-on-plug? If so, it's EU3 as the EU2 has a dizzy.

 

JV