| Author | Message | ||
     Lluís Gimeno-Fabra Prolific User Username: lluís Post Number: 264 Registered: 8-2007 |
Dear all, A problem with the car has popped out before holidays. I have a weird rough idle issue. When starting the engine in the morning the idle stalls to 200-500rpm for a few minutes (might even stop the engine). After one or two minutes during which I keep the engine idling fast with the gas pedal, all reverts to "closed loop" and it's fine, completely fine, idle is stable, performance is wonderful and so on. Starting from warm makes no trouble what so ever. Does anybody have experience with this cold idle issues? I am tending to think that it's either a leakage caused by a gasket which seals while hot... or That it's something only apparent in open loop control. Any ideas welcome. Lluís | ||
| Nigel Johnson Frequent User Username: nigel_johnson Post Number: 84 Registered: 12-2008 |
Thermo time switch? Regards, Nigel. | ||
| Lluís Gimeno-Fabra Prolific User Username: lluís Post Number: 265 Registered: 8-2007 |
Thanks for the fast reply, Where do I find this gentleman-switch? Is it the so called engine timer? Lluís | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2669 Registered: 4-2003 |
Lluís, the thermal time switch was deleted when the first Motronics came along. You may however have an issue with a Motronic coolant temperature sender (it is a separate sender from the one for the gauge by the way). It is located on the thermostat housing. Just a guess. Look up ECT in IETIS, Engine Management Systems 1994-1998 (TSD5501) for your M3.3 system. RT.  | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2670 Registered: 4-2003 |
ps: the thermal time switch (ie on K and KE2 cars) is only active when cranking the motor cold, and does not affect idle in any way. It purely activates the cold start injector during cranking and nothing else. Of course, M3.3 has no cold start injector as it is all controlled by the Motronic via the fuel rail. M1.3 has one, but it is controlled by the Motronic only, and has no thermal time switch. RT. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2671 Registered: 4-2003 |
pps: that Engine Coolant Temperature (ECT) sender is a Bosch 0 280 130 026 available for roughly EUR20 at the right places, or even on eBay. Rather than trying too hard at diagnostics, you may consider just throwing in a new one and trying it out to eliminate it from the equation. RT. | ||
| Nigel Johnson Frequent User Username: nigel_johnson Post Number: 85 Registered: 12-2008 |
Lluis, I'm sorry for leading you astray. I was only guessing. Thanks to Richard, we have both learned a bit more. Regards, Nigel. | ||
| Lluís Gimeno-Fabra Prolific User Username: lluís Post Number: 266 Registered: 8-2007 |
No way, do not be sorry, on the opposite, it's all useful information for others. I re-dismantled the Idle Speed Control Valve which I had cleaned making things worse, despite rotating freely with no electrical signals applied to it, I noticed that it had a hard spot (sticking) when electrical power was applied, probably due to the shaft moving slightly. I rotated it carefully with the fingers whist applying electrical power and it moved. Yesterday evening and this morning idle was perfect. Thank you very much and thank you both for the input. Let us hope, with a bit of luck, that the problem is solved. Lluís | ||
| Lluís Gimeno-Fabra Prolific User Username: lluís Post Number: 267 Registered: 8-2007 |
hi again, By the way and just to have a full threat and hopefully not need to come back to you. The ISCV in our cars is a twin coil motorised rotary valve which bypasses the throttle and identifiable as a bright cylinder on the intake, it works on duty cycle basis and very probably it is full of dirt (will be in many cars, as our turbo bushes and crankcases vent oil vapours to the intake). I have the impression that oil droplets tend to condensate there and at some point it will block make cold idle unstable, when hot the idle improves. It was very dirty in my car. It must be cleaned every 40000 miles or so according to the Service Book, but when you clean it, do not do it like I did (badly with WD40). Make it point down and spray it well with carburettor cleaner and let it dry. Repeat several times until it moves completely and freely, test it and repeat until operating well. Be informed however, that in case your ISCV is blocked by dirt, the might have an acceptably rough idle when cold that smooths out when hot but the ISCV might be broken as the electromagnet may have not resisted the electrical effort trying to move it. Cleaning it will, far from improving things, make them much worse as it will tend to close and stall the engine. It's Bosch 0 280 140 515. Best regards, Lluís | ||
| Nigel Johnson Frequent User Username: nigel_johnson Post Number: 86 Registered: 12-2008 |
Hi, on my old 420 se Merc the ISCV would stick and the idle would increase to 1100rpm. That really used to batter the transmission. I'm glad its sorted Lluis. Regards, Nigel. | ||
| Lluís Gimeno-Fabra Prolific User Username: lluís Post Number: 269 Registered: 8-2007 |
Crappy, Beautiful cold idle... and then pffff... today at full acceleration tons of black smoke and poor performance. something is definitely wrong with my EMS. I almost need to "pump" the pedal lightly to get the engine to run properly. I just ordered an O2 sensor, which must be bad anyway after 50000 miles and for the safety I will order the ECT sensor... The day after tomorrow I wanted to take her on holiday... I guess it will be the old faithful Jaguar. See you, Lluís |
