Hello, I'm new to this forum,

I owned a s40 2001 with 80000 miles. I bought the car at 70000 miles and its not been up to my expectation till now. Recently, I was going to work in the morning, after 20 minutes, going down a hill, I lift the foot of the gas and the engine rpm started to go up and down. i felt the transmission going from neutral to drive gear (around 60 mph). I then put the car in neutral (still at 60 mph), then the rpm went from 1000 to 2000 in about 2 second for a complet cylcle (1000 to 2000 to 1000) and kept going as long as I want. I then reengaged drive speed, the rpm was still moving, like the first time it went wrong. I then had to stop (stop sign). I drove up a hill, no problem. But as soon as the car has no load on the transmission it goes from neutral to drive, wich gives very strange and unsafe feelings.

I then entered a town, so I had to drive below 30 mph. Then, the transmission worked like it never had any problem.

I'm also having cold start problem in warm wheater condition (summer time). I ordered a fuel pressure regulator that I'll change next week. I have a CEL on that say misfire cylinder 3 and 1. I change the 2 ignition wiring, and the plugs. If the FPR doesn't help with the misfire, I'll replace the coil.

Do you think the transmission problem could be related to engine problem? The vaccum line look ok.

Thanks for your help

 

I would try cleaning the throttle body and idle motor.

 

Thaks for your quick answer. Where is the idle motor located? How do you "clean" it? And how do you clean the throttle body? The throttle is drive by cable, and not by wire, how could it be affecting the rpm that fast?

regards

 

The idle motor is screwed onto the front of the intake by the throttle body. Remove it and use carb cleaner to clean it.
Also use a rag to clean throttle spray some carb cleaner on a rag and wipe out the throttle body.

If there is alot of build up it can slightly throw the TPS off some and not make the idle motor work properly either.

 

Hello tech,

I cleaned my TB and Idle motor. I still have the problem. When I go down a hill, sometimes, the tranny wants to shift to neutral and then come back to drive. I did it 6 or 7 time last week. When I put the car in neutral, then the rpm goes from 1000 to 2500 rpm thn back to 1000 rpm repeativly. What do you suggess to do?

I have 2 crack coil that I'll replace this week.

 

I wonder if the idle motor is bad.
Check engine light on? If so get the codes pulled.

 

Hello tech,

After the car strange behavior of hunting at idle, it became a security issue, so I took the car to a Volvo specialist (not the dealer). I had the coil change (both) to get ride of the misfire problem. When I picked up the car at the shop, it had no misfire at all, it ran better than before (when I bought it). It was snowing as hell. I drove the car home, the DSA kept going on because of the slipery condition. I noticed a strong smell of fuel when the DSA was on. Is it normal? After about 10 minutes driving, I came to a red light. And then guess what, the misfire came back pretty bad. I stoped the engine about 10 minutes later when at home, and then restart it right after. Bang, the CEL came on, again ;-(. I changed both coil, both wire (for cylinder 1 and 2), all spark plug (volvo spark plug), and inspected all vaccum hoses. (With smoke) The mechanic (he has Vadis) told me that the fuel ratio in the computer was set at -4 when he inspected it. He said it means that the car injectec more fuel because the ECU thinks the system is lean because of the misfire. He said that he reset the fuel ratio to 0 (can vary from -10 to 10). I'm wondering if it is that fuel ratio in the computer that throw the misfire all over the place. The code when I bring the car to the shop were, misfire cylinder 3 and 4 and system too lean.

What do yo think the misfire can be?

And by the way, my misterious idle problem seems to have disappear!

Thanks