High Engine RPM while driving

[volvojj]

Originally Posted by StrongSpearWorks

The 25+ year old EC1 connector that lives next to the block and under the manifold can get brittle with time, as can the wiring. Mine was so sloppy it wouldn't make a useful connection any more. I snipped it off, spliced on a new one and put heat shrink over it all. Fixed that issue that time.
The ECT sensor is a known weak point in the LH system (any VAG owner of a similar vintage will tell you the same &#129315. Sometimes they last for 20 years, sometimes 18 months. When they fail they can produce all kinds of odd behaviour, even if they are apparently working (resistance and voltage are in range at a sample of temperatures). If it does transpire to be the sensor that's faulty, get a Bosch one; they're more expensive, but experience has taught me buy cheap, buy twice.

Many thanks for your replay and explanation about the problems with the connections.
I have uploaded some photos and video about fixing connectors and wiring:
> https://www.youtube.com/watch?v=GTRMJ937vDE
> https://www.youtube.com/watch?v=mNZq6PuOi5c

I think I understand about changing a connector on a existing wire (according to the first video). But what if the wire is damaged, do you simply cut the damaged part of the wire and solder an extension (as per the second video), or is better to install a whole wire (and where do you find/order a complete wire?

Also, may I ask if you can recommend some links about where can I order sensors and connectors (please also see my reply to RollingThunder).

Kind regards

[baggy798]

The ECT sensor is an EV1 connector, same as the injectors.

https://www.ebay.co.uk/sch/i.html?_f...=ev1+connector

You could go to a junkyard and cut them and a section of wiring off another B230F/FT/ET.

I would crimp them but you can solder the wires too. (and only the damaged bit)

You probably won't find replacement connectors for the dash temp sensor with the D shaped connector (like in those two pictures), but red/blue female bullet connectors might fit.

https://www.ebay.co.uk/sch/i.html?_f...ctors&_sacat=0

Or junkyard again.

[RollingThunder]

I ordered my temperature sensors from FRF Volvo as we get a good discount with them.

1362645 £33.30 + VAT
1346030 £45.90 + VAT

Yes, thats the discounted price So still not cheap, but they'll be top quality and will last another 20 years hopefully.

[StrongSpearWorks]

Originally Posted by baggy798

The ECT sensor is an EV1 connector, same as the injectors.

https://www.ebay.co.uk/sch/i.html?_f...=ev1+connector

You could go to a junkyard and cut them and a section of wiring off another B230F/FT/ET.

I would crimp them but you can solder the wires too. (and only the damaged bit)

You probably won't find replacement connectors for the dash temp sensor with the D shaped connector (like in those two pictures), but red/blue female bullet connectors might fit.

https://www.ebay.co.uk/sch/i.html?_f...ctors&_sacat=0

Or junkyard again.

Indeed. My car doesn't have Air Con, so had the spare EV1 floating about near the alternator. I appropriated that and used a couple of crimp connectors that came with heat shrink already in place. It was a bit of a squeeze getting the heat gun in there and aimed correctly... but it all worked out in the end (a small gas powered soldering iron with a heat attachment would have been a lot simpler, but I didn't have one at the time).

[TonyS9]

Originally Posted by volvojj

To: TonyS9 –Regarding your question about the speedometer - it is working. May I ask what do you mean by “…you need to check the speed signal is getting to the fuel ECU…”? How is this done? Is it done with computer software?
I rarely use full throttle, at most 3000 RPMs, most of the time around 2000 on open road. Have not checked for faulty engine codes (the mechanic’s software could not connect). I am trying to organize somebody else to have a look.

Kind regards
The model of the car is 1996; 2.3; 99KW; B230GK.

You can check the OBD but you need a readout flasher in 96, which you have to build, its not OBD2 despite the similar connector.

Otherwise you need a scope or pulse reader to check the signal. It is basically a wire connecting the ABS to the fuel ECU.
You could try using full throttle and see if that does it, or from a cold start in the winter, you will notice the rpm drop when you stop, this is determined from the speed signal by the fuel ECU, so if that works then its getting a speed signal.

Other causes are air leaks, but are more constant than random appearing.

[volvojj]

Hello,

After almost a year I would like to let everybody in this thread (and others reading it) that the problem with the high engine RPM while driving (without pressing on the gas paddle) has been finally solved.

The problem was with faulty Coolant Temperature Senor - CTS.

The reason it took me so long to repair it, was not that the problem and repair were complex, on the contrary changing the sensor was easily done by the mechanic. I spend a lot of time waiting for the car parts: 1/it took me some time to order and receive the sensors (CTS1: engine to ECU Bosch and CTS2: engine to dashboard/cockpit display) - I have ordered them from skandix.de in Germany and then had to organize delivery home; 2/my mechanic is from a town that is about 200km from where I live - so setting appointment was prolonged; and 3/ I was walking more and driving less, and when I had to drive I used the smaller second car .

Still I drove the Volvo now and then (at least once a week to keep the car in shape) with the familiar symptoms of high engine RPMs, with the problem usually occurring once or twice in the first 2-3 minutes after starting the engine (on a cold start) and lasting (high RPMs) between 10 and 20 seconds. This of course is very unpleasant and disturbing if you are in traffic jam, as you have to drive slowly and stop frequently - while at that time the engine can go up to 2000-2500 RPMs - so you either have to keep your foot on the clutch all the time or to keep the gear in idle.
A new symptom that occurred 2 months prior to the car repair was that I had problem with starting the car after driving it a while (when starting it on warm engine - warm start). After two-three prolonged tries (cranking the engine) and pressing the gas paddle, the car would eventually start.


Finally - all these problems were resolved after replacement of the CTS sensor and the car is now driving without any of the problems.


I would like to thank everybody that contributed to this thread as you guys have helped to correctly identify the problem. The mechanic actually was skeptical that this would solve the problem - he was thinking that I need to buy a new idle control valve as the one that I installed was second hand (see my first post in the thread where I explain what else I tried to solve the problem).

Again thank you and kind regards.
I will be glad to answer any questions you might have.