My son recently began having this problem with his 90 240 wagon. When first cold starting, it cranks and runs very roughly, you can smell it dumping fuel. Then it chugs as if its hitting on maybe two cylinders. If you hit the pedal right away, it dies. However if you let it chug a bit, then try to gradually rev it up, it seems to help. It will belch a big black cloud, then run ok after that. If you fail to keep it going initially, it won't start again.

We both research extensively on the internet and found a few posts with EXACTLY the same symptoms, but No one EVER replied with the fix... EVER.

It's extremely cold here so there's not much time to be outside chasing our tails. lol

Ideas, things looked at;
It has a new cap, rotor and wires already. Also plugs.
FPR is ok, no obvious leaks thru diaphragm.
Brand new coolant temp switch was installed.
New In-tank fuel pump (AEM320) and the in-line pump deleted.
New fuel filter.
Replaced the ignition coil.
No vacuum leaks.

Thinking maybe injectors leaking?
No engine codes..

Ran diagnostic procedure.. everything ok and heard the injectors fire and the air idle solenoid working.

After the car is warmed up it will restart fine.

Any ideas are appreciated!

Cheers,
Mike

 

If you remove the plugs and look into the bore with a flashlight while someone turns the key to prime the pump in position II (not turning the engine over), you should be able to see a stream of fuel if an injector is leaking.

 

Which of the parts installed that you list came before or after the issue at hand?

I really like your idea of deleting the inline pump. I recently had a main pump failure where my main pump was dumping fuel from the body of the pump. Scary. Hopefully this is not part of the problem; I am really interested in doing the same mod.

Seems like the flow rate of the pump you installed is correct for the car at least on paper; at 320 lph at 2.64 l. per h.p. it should support 121 h.p.

 

My 94 940 Turbo is doing the same .. still have not solved. I am beginning to think its ECU

 

Last night I replaced my plugs. Installed NGK BPR6ES plugs. The rough start symptoms are still there. Any other ideas? I could try swapping ECU's, but I believe it will still do the same thing.

 

Have you replaced your AMM\MAF?

Old MAFS can cause rich fuel mixture symptoms, they usually wear out from excess eat in the line. In the airbox you have a mechanical thermostat, these frequently failed in the "open" position, leading heat to build up and wear out your MAF, leading to start up issues.

To test this, unplug your MAF with the ignition OFF, then try starting the car. It'll run rich if it starts, and if it does your MAF is bad.

Be careful with the plug as it has a thin metal clip that can fling off, and do NOT plug it back in until the ignition is off. Plugging\unplugging with the ignition going can fry your MAF or ECU.

 

I have tried unplugging the MAF/AMM when the car won't restart after chugging and dying. It doesn't make a difference in trying to get it restarted. Also, the car is +t'd and there isn't a stock air box setup. It's currently running a 740 turbo setup but with a cone filter on the MAF, instead of being in an air box.

 

Try swapping in a turbo ECU if you haven't, or use a mega squirt.

You should list your mods as one of them might be causing issues, your cone filter could be throwing the mixture off for example.

 

I do have a turbo ECU/EZK. Using 850 turbo injectors in the car which flow almost identical to green-top turbo injectors, without having to wire in a resistor pack. Using a 3 bar FPR.

The entire build can be found on my youtube channel.

 

I'm sorry but with so many mods theres only so much advice I can give.

For anyone else reading this thread I advice to watch one of those videos, then this one:


I'm thinking that those burnouts may've broken something else beside the IAC and carbon canister vacuum lines.

 

It's a stock turbo 740/940 swap..... EVERYTHING from a FACTORY setup. People describe the issue I'm having on their, also, FACTORY/STOCK cars.

 

Maybe this thread will be of use?
https://volvoforums.com/forum/volvo-...-issues-50270/

 

is it a LH2.2 (up to 1989) or 2.4 (1990+) ?

does it use a cold start injector?

 

Hey, Pierce. It is a 1990 LH2.4 car. The car came factory with a cold start injector, however when I did the turbo swap, the ECU/EZK from the turbo car do not use the cold start injector, so I unplugged the injector connector. The cold start injector is still physically there to plug the hole in the intake. It ran perfectly fine for a long while, then just started doing the strange chugging and sounding like it's running on 2 cylinders when cold-starting for the first 15 seconds that it runs. I clear the chugging by waiting a few seconds and then adding throttle to "clear" out the unburnt fuel (which makes a cloud), then it sounds like it runs on all 4 again, and runs great. If I add throttle too quickly while it's chugging, it'll die instantly and won't restart for a long time. I'm completely stumped.

 

Pierce - this is the very same issue I am battling with my 94 940 turbo .. I hope in the end this thread will post the cure and if I find it I will post as well.

 

I was asking what the 740 turbo donor was, not what the car came with.

it sounds like you mixed and matched parts between the 740 turbo donor and the original 240 non-turbo. so you're using your 240 engine harness and intake manifold? mix-and-match makes remote diagnosis/guessing even harder.

just curious, did you replace the 240's non-turbo fuel pumps with the higher volume pumps for the turbo system? it takes a fair bit more gasoline per minute to get 160HP/190 ft-lbs (turbo) than it does to get 115HP/120 ft-lbs (non-turbo).

 

The OP replaced the 240s pumps with a single high performance AEM320, a pump designed for both NA and EFI Forced Induction.

 

yeah, he's got a frankencar, he's on his own here. "It's a stock turbo 740/940 swap..... EVERYTHING from a FACTORY setup. " ? not exactly, and not worth trying to guess what might be going wrong.

 

Hi all,
Thanks for the replies to my sons posts. As mentioned before we both read through many postings regarding this same issue with 740,940 and 240 cars as well. I really don't think its a Frankenstein issue, as it ran great, after the turbo conversion for quite some time. I see 240nc has the exact same problem with his 940 turbo, which I'm going to assume is stock as well.

After some thought, I'm wondering if it could be a leaky injector... Perhaps the last time the car is shut off, it slowly drips one or two cylinders with gas overnight, then is essentially flooded at the first start attempt in the morning. After it runs and you goose it a few times, it clears up and seems ok. I'm sure the injectors we installed had quite a few miles on them already. So, when the weather gets a bit warmer here, we may try and install another set of known good injectors. I suppose I could try running a tank of injector cleaner, but if it's some sort of mechanical internal defect, cleaner won't do it.

Perhaps it is something as mundane as poor grounding... I believe the injectors fire by grounding them.. With a car this old, I should probably go over all the grounds closely.

I will post my findings and maybe this will be the one post with a happy ending and the problem being resolved. Any other ideas, suggestions or revalations are welcome.

Thanks, mike

 

the ECU itself grounds the injector signal to fire it. it does this via a power transistor, and the actual ground wire it uses is one of the two ground points connected to the fuel rail bracket. that ground point is used for 'power' stuff, and the other one is used for 'signal' stuff.