87 8v 900 sputtering initial acceleration

[Focal]

Hey guys, I am a pretty new Saab owner (about a year), and a new poster to this forum. I have a problem with my 1987 8v 900. (I did search around a little, but had a hard time knowing what search terms to use, I'll explain later)

I was having some problems with the car idling and running smoothly, and since I have only had the car for about a year and a half I decided to replace some of the inexpensive consumables. I replaced the distributor cap and rotor, bought new spark plugs, cleaned the throttle body and ran some sea-foam through the engine. The plug wires look like they were replaced recently, and have no apparent oxidation on the ends or wear-spots on the wires.

I have not replaced the spark plugs yet, I was waiting until after the sea-foam treatment, and discovered I need a longer socket extender. I am up at college and so I don't have a full tool set up here with me.

Anyway, the idle is much smoother, the car accelerates better once it is warmed up, starts up quicker, all of the things you would expect from doing these upgrades.

The issue I am having, which I had periodically before doing all of this maintenance, and am still having right now is that when the car is warming up it sputters and looses power when I go to accelerate. When I apply throttle it sputters for about a second, and then picks up and goes. Once it is above 1500 rpm it runs great, but it's just that each time I stop and go to pull out into traffic I have to plan ahead and give it gas before my window and hope it is making power by the time I go to pull out.

Unfortunately I have a short commute (not much time to warm up) with lots of stop-and go driving, so this is pretty noticeable.

My question is, will this go away when I replace the plugs later this week (when I get time after work)? Because it is just as noticeable now as it was before, that's why I was concerned. If there is something easy for me to check/fix while I have the hood open in the next few days, that would be great.

Thanks so much for the help guys.

[SpecialTool]

8v cold running problems are often caused by a faulty warm-up regulator AKA control pressure regulator. The WUR regulates the fuel flow to the injectors -- when the engine's cold, a properly functioning WUR keeps control pressure low (20-30psi as against a normal 45-50psi) which allows more fuel to the injectors.

It's not really an easy fix as you need a fuel pressure gauge and some special line and fittings. My advice would be to find one at a junkyard and swap it in -- you're bound to need a spare someday!

[Focal]

Are there any easy ways to rebuild/clean the regulator? If replacing the plugs doesn't do it, I can certainly go try to find one of those, but if I can avoid having to buy one I sure wouldn't mind.

Any other ideas?

[Jim Mesthene]

Remove the Pressure Impulse Contact (the plastic thingie with the vacuum line and 2 wires mounted on the Fuel Filter).
Remove the 4 screws that hold it together.
Open it and discard the Spring inside.
Reassemble and Refit.

[jetman]

Make sure that you have installed the stock spec ignition components. Especially plugs. If not, the 8 valves are notorious for running poorly.

NGK Plugs, Bosch cap & rotor, bougicord leads. Our cars just run like junk without them, even when you think you're doing it a favor by installing more expensive parts.

Also, make sure the throttle body is clean and the air flow plate (Under the rubber bellows) is clean and seating well in its opening.

[Focal]

Originally Posted by Jim Mesthene

Remove the Pressure Impulse Contact (the plastic thingie with the vacuum line and 2 wires mounted on the Fuel Filter).
Remove the 4 screws that hold it together.
Open it and discard the Spring inside.
Reassemble and Refit.

What is removing the spring going to do? Does this bypass something to fix a problem? I'd just like to know what side-effects I could expect from removing that spring.

[Jim Mesthene]

Originally Posted by Focal

What is removing the spring going to do?

It makes the Pressure Impulse Contact more sensitive to vacuum drop.
There was a Service Bulletin about it (1988?).

[Focal]

Originally Posted by Jim Mesthene

It makes the Pressure Impulse Contact more sensitive to vacuum drop.
There was a Service Bulletin about it (1988?).

Thanks Jim, I finally got around to removing this spring (after some ignition wire woes) and now it runs MUCH better!

[JonoM]

Hi Guys. This sounds almost exactly the same as the problem I'm having with my 1986 900i. This might sound really stupid, but where is this WUR and what does it look like? Will mine be the same, such that I can try removing this spring to see if it helps?

[Focal]

JonoM, the Pressure Impulse Contact which is located on the fuel filter is a separate item from the Warm Up Regulator. Removing the spring from the PIC was a VERY quick and easy job, it only took a Torx and a regular Phillips screwdriver, and about 5 minutes.

The WUR is a different item altogether.

[JonoM]

Hi Guys,

Finally got time this weekend to work on the car. I've just pulled out that vacuum sensor and there was indeed that spring inside. I've removed the spring, but noticed on the top there was quite a bit of oil. Now being sensitive to vacuum, I'm thinking there shouldn't be any of that oil on the top. Would I be correct? I've attached some pictures so you can see what I mean.

Cheers

[JonoM]

Since removing that spring, the car is running worse on idle. I drove to the bottom of my street, came to a stop with the clutch in, and the engine just stalled. Then had a nice task getting it started again. Weird thing is, it now feels much smoother under acceleration when it's cold. Idling speed is definitely lower (about 500rpm now). Any suggestions?

[RickyS]

Jim Mesthene

Remove the Pressure Impulse Contact (the plastic thingie with the vacuum line and 2 wires mounted on the Fuel Filter).Remove the 4 screws that hold it together. Open it and discard the Spring inside. Reassemble and Refit.

It makes the Pressure Impulse Contact more sensitive to vacuum drop.
There was a Service Bulletin about it (1988?).

Don't reconise this pressure impulse contact thing. Was it fitted to UK models? There is not one on my 8v 1986 or 1984 as far as I'm aware.

[milos]

Don't reconise this pressure impulse contact thing. Was it fitted to UK models? There is not one on my 8v 1986 or 1984 as far as I'm aware.

Me neither, I was looking for it on my '86 & '87 8V's and could not find it.