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91? 940se (*wont start*) (1.4 year 2022 bump)

Ozzyd2

New member
Joined
Jul 11, 2017
Howdy fellow Volvo nuts
Greetings from sunny California, Los Angeles
Got a 91’ 940se wagon
Did a few mods to my wagon and haven’t been able to start it up successfully, gonna explain my dilemma and see if any of you guys can share some advice cause I’m at a standstill at the moment...

Mods done:
Machined head (530)
Ipd turbo cam
Ipd adjustable cam gear
Green injectors (relay mod)
15g turbo (19t internals)
3” MAF
3” downpipe/full exhaust
Blaster coil
eBayChip (stage4)on both ecu and ezk (gold box)
Welded diff
Full ipd suspension
A/C delete
Oil catch can
Dual stage boost controller


Engine cranks over and starts up after a few times but needs throttle to be applied and moment throttle is released the engine cuts off, no real idle. Wondering if maybe someone here can help and shed some light cause I’m head scratching at the moment.
Much appreciated.

*update*
the car turns on and stays on, idle is solid but afr bounces from 12-14, same thing under load.
is there such thing a negative boost?
the car idles at like -12 psi and never really builds boost in the positive, any help ?vacuum lines seem ok.

also foes anyone have any advice or guide for speeduino being installed into these cars, i have a unit ready to go but don't want to hack my harness unless im sure what im doing. appreciate any advice


(looking to buy a 740/940 clutch pedal assembly, if you have one let me know)




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Did you have those issues before you did any of the mods?

Start with the easy stuff first.
TPS and linkage is correctly adjusted? Throttle body is clean?
Idle valve is clean and functional?
 
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My megasquirt car likes to idle about 12.5:1.

LH just driving around is going to bounce around some. If you got on the highway and we’re steady state cruising you might see stoic afr’s. That eBay chip is going to do who knows what to your afr’s though.

Negative boost is called vacuum. You’ll be in vacuum when the car is idling, when you’re coasting, pretty much anytime you let off the throttle.

From my experience, when it doesn’t want to idle, you usually have a vacuum leak somewhere. Would double check all your charge pipe clamps are tight and all the vac lines coming off the intake manifold are on snug.
 
The fact that you have only 12" of vacuum at idle tells me there's something mechanically wrong, like the valves are shimmed too tight, or the cam timing is off. If it's not making boost, I'd start with cam timing. I see you have one of the ipd cam gears that's fixed in adjustment, I (and others) have found them to be rather dubious in accuracy. If you have a stock gear to use, for the purposes of this exercise, I would put it on. How much was the head milled?
 
The fact that you have only 12" of vacuum at idle

Are you sure it should be more, I always thought that's around the normal figure?

I'm seeing the same number at idle and my engine is running perfectly fine for the last years (at least I wouldn't know about any issues...)
 
Are you sure it should be more, I always thought that's around the normal figure?

I'm seeing the same number at idle and my engine is running perfectly fine for the last years (at least I wouldn't know about any issues...)
Probably depends on your cam, I'm around 20-21" at idle with an ipd turbo cam.
 
Are you sure it should be more, I always thought that's around the normal figure?

I'm seeing the same number at idle and my engine is running perfectly fine for the last years (at least I wouldn't know about any issues...)

You would have to have a SERIOUS camshaft for that. Normal is probably around 20-22 or so, give or take. The first engine I built when I was a kid was a 283 Chevy with 2.02"/1.60" valves, 8.0:1 compression and a reproduction 350 hp 327 cam (really long duration). This was an abysmal combination that wouldn't spin the tires, even with a 4:10 axle. Anyway, it also ran fine, but drew 11" of vacuum at idle.

If you've got a stock engine that you've put a cam in and it gives you less than 15" (really I'd say 17 but I'm not trying to split hairs here) or so at idle, I'd bet you really feel that cam "come on". If you like it, that's really all that matters, but the total area under the power curve is compromised.
 
I have an unmodified block / head as far as I'm aware, so my B230FT should have a T cam.
Guessing I should start looking somewhere to fix this, but what? No vacuum leaks as far as I'm aware and I've gone through the whole hose system last year.

OP, sorry for derailing your thread.
 
so after starting the car again booost gauge reads -14psi and when i give it gas it drops to -22... i have not driven the car yet like this, just revved in idle. doesnt ever creep in to the positive spectrum oof gauge but i can hear the turbo spooling healthy and blows off smoothly. very confused at whats happening here, cant remember how much the head was milled and will try to find a stock cam in the junk...

one more thing, oil was milky today when i checked it... could i have blowby or bad head gasket ??
 
There really isn't a way for us here to tell what is going on. Did the car ever run ok? Or did you do ALL the work at once "to save time" and now you have a heavily modded vehicle that doesn't boost?
 
so after starting the car again booost gauge reads -14psi and when i give it gas it drops to -22... i have not driven the car yet like this, just revved in idle. doesnt ever creep in to the positive spectrum oof gauge but i can hear the turbo spooling healthy and blows off smoothly. very confused at whats happening here, cant remember how much the head was milled and will try to find a stock cam in the junk...

one more thing, oil was milky today when i checked it... could i have blowby or bad head gasket ??

Vacuum decreases as you increase throttle opening. As vb242 said, Revving in idle will NEVER go into positive pressure (boost), the engine has to be under load to generate the backpressure needed to spool the compressor. If you power brake it, you may get into positive pressure. Seems pointless to worry about that until you sort out the basics. Did you try removing/capping that vent filter as suggested previously. Who did all the work for you? Have you contacted them?
 
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