As seen from my previous posts, Ive been having issues with getting my volvo started and running. I can get the car running with the MAF disconnected. It does take about 20 secs of cranking and actually giving the accelerator some gas to get it running though. When its running, it runs a little rough in lower rpms (under 1000) and smooth if I give it some gas to go above 1000rpms approx. If I make an attempt to plug the MAF back in, the car will shut off immediately.

I feel like I am chasing several issues all at once just to get a running vehicle.
Ive already replaced the cam sensor with a known working one and that helped me get the car running, as before it wouldnt even start or idle at all.

I still havent had a chance to check fuel pressure yet, but I am hoping to do this soon.

 

If plugging the MAF in causes the car to fail to start, I guess you will have to replace it.

 

Like you said, I also think you have multiple issues. Ck the fuel pressure and I am guessing you have multiple vacuum leaks as well.

 

Ok so I bought a new maf to test with and it gives the same results

I can get the car started without it but when plugging it in (even the new MAF) the car will shut off.

I can get the car started without the sensor plugged in still, although it takes about 20-30 secs cranking.

I know alot of people here have stated that it could be the fuel pump or the fuel pump relay, but while the car is idling, wouldnt it be effected by either of those if it was malfunctioning?

It is also driveable and I took it around the block without really any issues.

Im begining to run out of ideas at this point and the frustration is really building considering the amount of time and money put into the vehicle.

 

If the fuel pump is okay? then the fuel pressure problem is likely to be caused by the fuel pressure regulator being defective.
Low fuel pressure would make the car difficult to start.
A check of the inline fuel filter would be a good idea also.
The Schraeder valve on the end of the fuel rail should squirt fuel at a good pressure if all is okay. (caution with spraying fuel)

 

You don't have to guess whether it squirted fuel far enough. Use a tire gauge. It works fine.

It makes some sense (to me anyway) that if you have massive air leaks, it might run okay in "guess the airflow" mode but then not be able to run with the MAF plugged in. As you know, there is about 10 feet of piping between the MAF and the cylinders. There are a lot of places for leaks. The rubber elbows can get big holes in 'em. I don't know the best way to diagnose that at home. A smoke machine might be the ideal way, but you'll probably have to settle for a thorough inspection.

Normally I would recommend getting something to log OBD data, but in this case it wouldn't help you much. You could only look at the MAF airflow while cranking, since it won't run with the MAF plugged up. That is still useful if you can get somebody here to give you a baseline number for a car that runs.

 

What brand MAF did you purchase?

As mentioned, look real close at all of your intake and turbo tubing for tears, holes, loose clamps, etc. I would take all of them off and inspect them one by one.

 

Thank you guys

I will check the hoses, I really should just order new ones as the old ones are original and have almost 200K miles on them.

To be very honest I never thought a break in the line would matter, but Im also not really used to an MAF system. I mostly have Jeeps and they dont use MAF.

I honestly never thought to check the fuel pressure with a schrader valve, I was honestly going to pull the valve out and just clamp on a fuel line to a gauge


Last question, since I had bored out the manifold and installed a 760 Throttle body, I had to redo the hosing because of the larger diameter.
I didnt end up with the snabb piece but a larger 90 degree to connect the throttle body, I then found a small air filter which I connected to the idle air controller
Now here is the question, does the IAC need to pull air from the metered air of the MAF? The way mine is setup it is pulling it from the atmosphere.

Thank you guys again

 

Well, there's your gaping hole.

I haven't done that, so I can't say whether the symptoms you see are typical. But an obvious question has to be asked: Did it ever run right in that configuration? If not, I daresay reversing that mod would be a good little experiment.

 

While Im sure you are correct, I cannot reverse it as the original tubing will not fit the new TB and also was broken down very badly. I guess my only choice is to get one of the snabb units. I just cant believe that if people want to upgrade their TB then they are obligated to get the Snabb unit as there is no way to configure the car without the IAC connected to the intake air after the MAF...

 

Just to make totally sure, it would be easy to duplicate what you've done on a stock running turbo car and see if that has the same result. I don't have one here that runs, unfortunately! I could do it on a NA car I guess.

But it does make plenty of sense to me.

 

Thanks to you, I ordered a snabb silicon throttle body hose and now have the iac connected with the maf.
I can now get the car started(eventually) with the maf plugged in !!!

Once it is running it stays running and runs smooth, no uneven idle at the lower rpms like before.

The only issue now is that it does still take about 20-30 secs of cranking to get it to start.

I put a fuel gauge on the fuel line and it shows atleast 15psi (I do need to get a larger gauge as the one I borrowed from my father is for carbs so it maxes out at 15) I do know the fuel pressure does hold as well even when removing the key and shutting the car off.

My question is this, what should the priming pressure be? And how about during idle?

I can check that stuff next...

thank you again in advance

 

I dont know the actual specified fuel pressure in PSI for your model but for a V40 like my vehicle, the Haynes manual says 44PSI.
I would have thought yours would be over 40 ??

 

For '96 and '97 850 turbo (may be same for N/A; not sure) fuel pressure should be around 35 psi during cranking and idle. It will go up as manifold pressure goes up (boost) too; up to 55 psi at full boost (11 psi or so).

you can also try (while idling) pinching the return fuel hose with a pliers (for just a second); should see fuel pressure spike up to 80-90 psi.

 

ok so today I rented a proper gauge and here are the results

approx 50psi while cranking and once running it stayed at exactly 35psi

When I shut the car off the gauge stayed at a steady 35psi in the line as well....

Im now out of ideas of what to test...

The only way to get the car to start is to give the go pedal some pushes
A few times I was able to get it started within 5 secs with the gas pedal

I can always get it started but I still cant get it started easily... or without the gas pedal.

 

Well I would say you ruled out a fuel pressure issue...

I would be really surprised if you don't have more vacuum leaks to fix. With engine idling, did you try spraying carb cleaner around the intake manifold and hoses, all the way up to the MAF? If idle speed suddenly changes while spraying, you found a leak. Keep a fire-putter-outer nearby just in case.

Other than vac leaks, a slow cranking starter will make for hard starts. If it cranks slow at all, get the starter rebuilt and ck the battery cables, battery, etc.

Bad or borderline crank speed sensor (on trans housing) could give hard starts as well. No codes, right?

I would also ck the throttle position switch (TPS). You can ck it with OBD2 scanner if you have one. Should show some low % to high; like 10% to 90% IIRC (don't expect 0-100%).

Oh yeah, low engine compression will also cause hard starts; have you checked? Stage0?

 

I will check again for vacuum leaks, Im really lost on where they could be..
It idles around 800, but when its in gear it idles at 700
It doesnt crank slowly and the starter is brand new..
Battery I had checked at auto store and also had it slowly charged there as well.
The battery cables I personally cut and stripped and reconnected to the battery clamps for better efficiency since the old ones looked crappy...

I will do a search for the crank speed sensor..
I have a scangauge and a generic handheld for the OBD2, can anything on the scangauge help? The generic handheld really only reads and clears the codes so it wont be much help

I do not have any codes as of now, I can say that the service light comes on after I have the car started and stays on a bit but eventually goes off.

As for the compression test, I did one months ago, but frankly am not sure I did it correctly.
I will most likely do it again...

From my reading on these forums, Ive read that people have issues with the fuel pump relay and have simliar symptoms as me. I know it seems stupid as I can eventually get the car started, but I may just jump that temporarily to see if I can get it started without the extra cranking
I read where someone had the same issues and that the starting was intermitten and once started the car was idling and running smooth, it was just the first start that was always an issue..

 

service light is simply a timer, so that does not come into play

 

You have confirmed your maf, fuel pump and fuel pressure as such to be okay but have you looked at the fuel pressure sensor being the cause?

 

What fuel pressure sensor?