surging idle

[Koots]

Spray cleaning the TB is a good way to get rid of carbon buildup, but leave most surfaces very dry. Try spraying a light spray lubricant, not WD-40, it is useful for many things, but it is not the best at any of them. I like Liquid Wrench, PB Blaster, M16 (local parts store brand) and any Wurth product (seems to make a solid product in every line).

This might help loosen up a sticky IACV, but it's just a free shot in the dark for you to try I've spent many an hour, fuming over "impossible" fixes, only to stumble on a simple answer after spending too much money and/or time. I hope that this knowledge can be useful in some way to another.

[BerettaMN]

Im willing to try anything at this point but I cleaned the idle air control valve and TB already. thanks! Oh and I forgot to add I tried starting it with starting fluid. Didn't start with that

[3X00-Modified]

Fuel pressure will drop at idle when the vac line is hooked up to the regulator, if you disconnect that the pressure should jump up to the ~43PSI... But it sounds like you have bad or stuck open injectors... You need to ohm test them and or replace them with some others. If adding more air to the situation causes the engine to start then your flooding it when not opening the throttle.

I would also try changing out your Coolant temp sensor, BUT This is all guess works since you really only have one test result posted to work off of...

If you can have someone scan the ECU with a OBDI tool then you can see what your sensors are reading and that would definitely point you in the right direction when it comes to repairing the issue, otherwise you'll have to just keep throwing parts at it.

[BerettaMN]

Thanks for the reply modified. Yeah it did jump back up in psi when disconected. I did replace the coolant temp sensor about a year ago, because of a fan not coming on issue. So it probably still should be good? Ill start looking for someone who can scan obd1

[3X00-Modified]

Its probably fine then... I would see if you can source a set of injectors, or ohm out the ones you have to see if any show up funny... and as another test, pull the rail out and turn the key on see if any are leaking.

[BerettaMN]

Sounds good. I went to get a service manual but they weren't in stock, ill have to remove the intake plenum to do this right? Sorry first time doing this. Also any one know what the ohm specs are for 91 3.1?

[3X00-Modified]

yes you'll have to remove the plenum to check for leaking... as far as the ohm test goes, they should be around 16-17ohms...

[felixGTU]

I thought the ohm should be between 12-12.5 ohms.

[BerettaMN]

I went and got myself a nice equis auto-ranging multimeter just now. all my injectors were at 12.5 or 12.8 ohms

[3X00-Modified]

According to Bosch the PN that should be on a 91 3.1L spec is 16.15ohms

Find the number on the injector and find it on this chart and see what it says.

I was using 0280150221

[felixGTU]

So the resistance on your injectors are good they may still be the problem because the filters in the injectors might be dirty or stuck open. I am also currently having problems with my Beretta also and it acting up almost like yours I still cannot find the problem.

[3X00-Modified]

Pull the injector rail and prime the pump, see if there are any drips from the injectors... That will tell you if they are leaking or stuck open.

[Money pit Beretta]

So it's 16 ohms for 3.1 injectors and 12 ohms for 3100's?

[scd88ga]

So it's 16 ohms for 3.1 injectors and 12 ohms for 3100's?

No, 3.1's and 3100's are both 12-13 ohm.

[Money pit Beretta]

It's weird that Bosch would list it a 16.