Hi, I just got this 740 (non-turbo sedan) and it runs really well. However, one thing I am not used to is the way it starts. The car starts up fine, but it just stays at a low idle speed, and therefore is somewhat rough at idle. I give the car gas and get the RPM's around 2k and it is very smooth, but I have to do that manually.

The car hasn't stalled, but the weather here hasn't gotten cold yet. All cars I have driven with fuel injection start up and go into a high idle and once warm the idle drops down, but I am not sure what to expect from the 91 740. I'm wondering if the car is just this way normally or if there is some problem with a valve in the air cleaner or in the computer or something. Thanks!

I've got an 1986 740GLE same thing. If the car is started under cold weather conditions she wants to idel at 500-600rpms. I then have to manually hold down the throtlle until she warms up roughly 1-2mins.

Any luck with this problem?

I have a 1990 740 and mine idle's about the same when cold.

I'll jump in this pile too.
Very low idle speed on cold start for my '89 740GL wagon!
I read in my repair manual that the coolant temperature sensor can adjust the timing on the B230f, so that may be an issue.
The only problem is that I just replaced it and when I run a diagnostic, it states that it is faulty.

I have an '88 740 and it does the same thing
It started out like that and then it got worse even though I changed the plugs and air filter.
it started stalling at lights and stop signs, so i'd have to put it in neutral and keep my foot on the gas slightly so it wouldn't die.
I took it to a friend and right away he tested his mass air flow sensor on it and it ran like a beaut.
So this is a possibility, the rough idle's a pain in the butt

Ok then after reading these posts my car is not normal.
Right now in the middle of winter in Montreal Canada I start my car in the morning -25C 0 F and it revs at 1k until it gets warm then drops down to 600 or so.

So either my car is working perfectly and yours are all broken or it's just possessed :)
On a side note my car a 89 740GL non turbo was made in Canada if that makes any difference.

wwdragon

My car's ('89 740GL) evidently not normal either. I start my car up on -10F days and it will idle up to 1500 even 2000 for around 5 seconds before bringing idle speed down to 1000 then eventually 600.

1989 740 Turbo I have been having this issue for years when it is cold. I have posted in multiple Volvo forums and haven't received a fix.

When it is cold it may start with a rough low idle. If you don't step on gas and get rpm's up it will die and not restart till it is good and ready usually the next day if warm.

A workaround is treating it like it is flooded. This requires more than one person but it was a life saver when I was stuck at a ski area. Pull off the electrical connection to all the fuel injectors. Have the other person start the car (amazingly it starts right away and runs till fuel runs out which isn't long) have them keep cranking while you reattach the fuel injectors and it starts. Keep it running and once it heats up it'll run fine.

I know from a previous fuel injected car that the injectors have to have a certain voltage from the baterry (11v?) or they won't shoot fuel. Course that was when it was 25 below. With the Volvo it just has to be near freezing.

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The 740 has a "cold start relay". Does anyone know what this does and where it is located?
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The distributor cap is notorious for cracking and causing similar problems but not my case...replaced multiple times.

This seems to me to be a sensor related issue. I just have run out of ideas and logical parts to swap.

Thanks all..

See above, I just read a better suggestion /solution to starting flooded engine rather than pulling fuel injectors....pull fuse 1, fuel inject/pump relay...duh

Here is what I have learned about my wagon symptoms so far.

There are TWO temperature sensors located on the drivers side of the engine block below the intake manifold for Bosch fuel injection systems.

The first sensor does nothing more than send a reading to the temp gauge on the instrument cluster.
The second sensor located behind the knock sensor reads the temperature of the coolant and sends a signal to BOTH the fuel ECU and the ignition ECU which can adjust the timing and amount of fuel being delivered!!!!!

I have one on order and will see if that is the case...now that it is getting warmer, I may not be able to tell, but I am pretty sure that is the problem.

My question is: why the hell the Sweeds would put 2 sensors in, when only one was needed?

just left car shop told i need a cold start sensor to fix low rpm, flooding, and staling