DavidI

Hi Folks,

In the last 6 months or so my car has sufferred from this very occasional (maybe 10 times in total over the 6 months?) loss of power.

It's always at low speed, say under 40mph, and the symptoms are what I'd imagine you'd experience with a fuel delivery problem - the engine is just about running but won't hold an idle (it will stall if I release the accelerator), occasionally sort of part-responds to acceleration (not cleanly, if at all) and I end up 'dancing' on the accelerator to try and keep moving while not sending the revs through the roof if it does catch. I normally try and pull over to the side of the road or to a minor road, and during the accelerator dance the engine normally catches and is then fine. It can take a couple of minutes.

This normally happens when cold, but has happened when the engine has been warm, too. When it happens, I can normally crawl along at 10mph or so, and if I get onto a decent road it normally disappears completely if I can get to higher speed. It hasn't yet happened at higher speed, but I am looking for a fix before it decides to....

I can always tell when the problem clears; other than now running normally, the car almost coughs, like it's spitting dirt or something through the fuel line, and after the cough we're away like normal. Once it's happened I tend to be OK if I get the chance to drive at higher speed, but it can recur minutes after one episode if I'm in town, though tends not to.

I only do around 2,500 miles a year, and most of those are at low speed - my commute is 5 minutes, so no chance for the engine to get warm, so I'm at 3k revs or less. A little over a year ago I had a top-end rebuild at JZM and everything, other than this, seems perfect. When it happened on Monday I had the opportunity to use the revs, and the car was perfect - then it happened again Wednesday evening. I can go weeks without giving the car a chance to clear it's lungs at decent speed.

I have changed the DME relay twice. I'm now thinking fuel pump, or fuel tank (I had a problem a year or more ago where the pressure in the fuel tank wasn't venting, and the car would misfire (different feeling to the one I'm trying to describe here) until I opened the fuel cap a touch. The fuel tank problem seemed to clear itself. Could it be distributor or coil related? Could these be intermittent and low-speed only?

I wonder whether anyone has had a similar experience? I'd be more comfortable presenting at least a theory if I book the car in, rather than just asking JZM to identify and rectify a fault they may not see for weeks or months.

Thanks for any feedback,
All the best,
David

Harry Apps

Try taking it for whiz around the M25 at the weekend and blow the cobwebs out using G 3/4/5 and let it get properly hot. Then start looking around the plug leads etc for condensation etc (old-fashioned damp problems) when its cold and before starting.

ras62

I had similar issues before I changed the O2 sensor. Now idle is fine and no other coughs or power problems.

koenig_roland

if had similiar problems and the problems are gone since my o2 sensor ist unplugged. I´m going to change the sensor next week and hope it won't come back...

try to unplug the sensor...

DavidI

Thanks All,

I've booked it in for investigation - I hadn't thought of the O2 sensor and I think sensor problems will show up on the diagnostics. If it happens before I take it in (Tuesday) I will unplug the sensor. If they cannot find any fault I will just have to drive more

All the best,
David

ras62

The fail mode of the O2 sensor is not certain, mine for example looked ok. Once changed the running problems disappeared. For what it costs I would get the indy to change it. btw my car didnt like having the O2 sensor disconnected one bit, it was almost undrivable.

koenig_roland

i did half of the way from munich to lake of garda and back to munich. Every time, i tried to reconnect the o2 sensor, the problems came back...

xdecock

Mine had (read seems soved but as It can sleep 3 month i'm still waiting) the same problem.

Seems to be fixed by changing the airflowmeter it seems to get sticky and not doing it's job. The cough out and the limited speed symptom are the same the random occurrence too but it happened on highway for me

xdecock

Mine had (read seems soved but as It can sleep 3 month i'm still waiting) the same problem.

Seems to be fixed by changing the airflowmeter it seems to get sticky and not doing it's job. The cough out and the limited speed symptom are the same the random occurrence too but it happened on highway for me

DavidI

Well the car was at JZM yesterday and was of course running perfectly. Diagnostics showed no recorded faults with O2 sensor or anything else.

I was describing the fault to Chris and as soon as I mentioned the 'cough' after which the problem clears, he reckoned dirty idle microswitch contacts.

They've given them a clean and we shall see. So far so good, and while it could be completely my imagination the car does seem smoother at very low speed.

Thanks everyone for your ideas.

jimq

I had the same type problem and it turned out to be a circuit board for the gas pedal. It would put it in liimp mode. I would turn it of and would drive normal and then happen again out of the blue. It finally stayed in limp mode. Not a hard fix but the part was $1K for what probably cost $2 to make.