Won't boost, misfires, stalling, hard start.

Every good penny you throw at this baked bitch is gonna be thrown after the last bad one. F'k it. Roached// Might not be this bad but you should have seen clues with the head off?



Find a good used engine and save yourself a lot of anguish.

Spare time: Pull the dead carcass apart and see if anything's salvageable.

Wtf is with people driving volvos so hot that they stop running? Your symptoms seem similar to the gold 91 244 **** show that we did the head on. And like I said, but didn't officially prove, the block was warped and or cracked.

I bet the motor is roached. It may still chooch but it'll never be like before.

I guess I haven't really had this problem before because I don't destroy my stuff.

I'm gonna start with what my lead tech said to do:

-Running compression test: must be at least 50 psi
-Leak down test
-Vacuum gauge

I learn a lot from the lead tech at each shop I work at. Any time I cant figure something out quicly , under an hour, I get to pass it up to the next guy and learn how he does it.

Maybe I should bust out the 4 channel pico scope and do pressure transducer analysis. Don't have pressure transducer, but I eventually want to learn how to find mechanical issues with one.

So far what you're describing still sounds like a vacuum leak. I've picked up a car and fixed a couple that were like that, when the AMM-turbo hose was mush and had a hole in it or had come off the turbo. The one I bought the guy said he could barely get it started, wouldn't go with any throttle, would just die, wouldn't snap, nothing with any kind of load, and it idled like crap. Made the deal, put the hose back on the turbo, drove the car home without issue, actually ran pretty good, even in bewst.

Intake hoses are fine. I have had em on and off many times now and they are good.

I brought a can of starting fluid with me today. That would help rule out any mechanical or ignition issues if I can get it started and keep it running.

I watched my lead tech diagnose a fuel pump issue yesterday with a snap throttle test on an older F150. Pressure was fine at idle but would drop way down after a snap throttle. He started with the filter and no change and then did the fuel pump and got it running fine and shipped it.


I plan to go to this car tonight and diagnose it. Let's hear which tools and methods ypu guys would bring.

other info is plugs are on the blacker side.

ZVOLV said:

I watched my lead tech diagnose a fuel pump issue yesterday with a snap throttle test on an older F150. Pressure was fine at idle but would drop way down after a snap throttle. He started with the filter and no change and then did the fuel pump and got it running fine and shipped it.


I plan to go to this car tonight and diagnose it. Let's hear which tools and methods ypu guys would bring.

other info is plugs are on the blacker side.

Click to expand...

Oh yeah my car was running like turd before when my in tank failed and put extra stress onto the in line. I replaced my in tank and got it working but the damage was already done. In line fuel pump would make a oscillating whine and car would run sluggish as heck(massive hesitation). Contrary to popular belief fuel pumps can "start" failing, it is not a back or white thing but can be in between too.

I also had to fix my radio suppression relay which I found that my mechanic was lazy as heck and just silicon glued the wires to the pins. I even had to replace my maf because there was a LH 2.2 maf in my LH 2.4 car lololol!!! Also replaced my fuel pump relay and crank position sensor for good measure. I did compression test, replaced fuel filter, and a hours worth of fixing to get the car where it is now. Just do your usual visual checks and you'll probably find the problem. Also many of my problems were found via codes, what does the obd1 system say? Mine in the past said "fuel injectors" which after I took them out was absolutely falling Apart. Once I replaced this, codes went away and car drove waaaaay better. Then it said maf code which after I put a normal lh2.4 in there ran evveeeen better. So basically don't underestimate obd1, it actually told me accurately what was wrong. Same with the fuel trim code. Replaced fuel pump and fpr and stuff and had good adequate pressure to the injectors.

I think I had a total of 5 codes. 4 of them I fixed. Last one I couldn't fix was crank position sensor, which was bull crap.... so I replaced my 563 ecu with a 937, and behold no codes and a amazing running car! It actually cranks too fast, literally .5 seconds of cranking before it fires up lol. And it's fast! I raced a BMW i3 SUV with 220bhp so I at least have that !

And let me tell u guys....never run a 2.2 maf in a 2.4 car, you should've seen how it ran lolololol! Well it wouldn't hold idle after unplugging the battery and during the relearn phase. It would die and I would have to start it up again to let it try and relearn idle, die for another 5 cranks until it figured out how to idle with the 2.2 Maf. Would have to also hold down the gas to keep it from dying. Once it learned idle though you were pretty much home free, however God save you if you removed the battery terminals.

Fumomike~ master Volvo tech

So sounds like you guys are telling me to load the parts cannon in my trunk and bring that with me mobile!?

The purpose of this thread was to hear what you guys have to say about diag techniques.

I work mostly on OBD 2 cars and I can usually glean some data off the scan tool via codes or live data to at least get some idea of what is going on, but codes can be misleading

I am on my 7th car today that I have serviced/diagnosed/repaired. The obd 2 ones were easy. The carburetor 1979 Hi lux that is running rich and failed smog, I didn't even know where to start!

Back to the 1990 940, I am gonna go at it tonight after work with a can of ether and see if I can get it started and running enough to try a running compression tests.

Again, which tools and methods would you guys bring to this one?

Leak down test or compression oil to squirt in the cylinder, can of either, that should be l.h. 2.2 or 2.4 rite? Wouldn't that have the diagnostic l.e.d.s on the fender? Volt meter, maybe a spare maf, check for fuel on the vacuum side of the fpr. almost sounds like the charge cooler is leaking, or maybe the distributor cap got overheated to and cracked

Arrived at vehicle. Started it. It idled but still won't drive. Would start missing and stalling at idle. No ether needed.

Running compression test was inconclusive. I need to get better at doing em and interpreting the results.

Stall and hard start once warm.

I shall fix this!

I left the spare block on my trunk.

Somebody probably boogered up the air/fuel mixture needle on the hi lux, they're very soft brass and need to be replaced if they get a little ring in them from screwing them in too tight. I had a 78 Corona with the same 20R and Rube Goldberg emissions carb. Have you checked the RSR on the 940?

https://youtu.be/138KUSoGyME

https://youtu.be/Ayy_zBE9yr0

Fuel supply? Both pumps running at least? Check B+ to the injectors while running, make sure it doesn't drop during a snap, in case the RSR can't handle the load (bad solder joints or dirty contacts).

Seems like spark is fine at low load (control side likely not having an issue), might be worth ohm'ing the coil and plug wires.

I'd bring a box of matches and a small can of fuel...

It's probably time to put a fuel pressure gauge on there or maybe ampclamp the main and tank pump to check for signs of life.

I got over 60 psi running compression on all 4 holes so that tells me the compression is good; so far the bottom end is checking out but I plan to re test. Good thing I didn't just condemn the block.


Total money spent on parts=ZERO!!!

I don't ohm spec wires. Never really means much to me. Usually the insulation goes bad and there are shorts.

RSR!!! Meh I also try to do tests so that I learn how to diag it next time instead of just getting lucky with the parts darts. Hmm voltmeter the injector positive you say.... I might just have to find a way to get a scope going so I can ampclamp em and see what data I can pull.

Oh I had a 2-3-2 fuel trim code last night! But I also had a MAF and ECT code but I caused those by unplugging em with the ignition on. I am not sure if the 2-3-2 fuel trim code was related or if I really am way off. I deleted and will see if I can duplicate it again.

oxygen sensor oscillates on the DVOM. Scope would tell me a lot more, but it's at least not pegged at .1 or .9v.


This is when OBD would be nice. I could scantool the fuel trim, injector pulse width, misfire monitors, etc. I guess I could scope the injector pulse width, but I am trying to keep this low tech. My $80 Hantek scope is glitchy as funk and I don't have a laptop anyways. I finally got my hands on a 4 channel pico at the shop but I don't wanna bring it.

I am trying to old school tbricker diag this thing! Thank you for the suggestions.

ZVOLV said:

I got over 60 psi running compression on all 4 holes so that tells me the compression is good; I am trying to old school tbricker diag this thing! Thank you for the suggestions.

Click to expand...

Put down the scope and open the book.

So without replacing any parts, what would you guys do to determine if it's a misfuel related misfire and power loss issue, an ignition related misfire, or a mechanical issue?

I may have to borrow the shops fuel pressure kit. Some of the $300 kits from the professional suppliers have the fitting I would need. Snap on, Matco, Mac, Cornwell etc. Usually the ones kicking around the shop are missing parts.

Wrong maf? Bad fpr ? Spark plug wires mixed up ?


But I'm probably blocked so **** it


You talk about parts cannon but you throw the Obamacare diagnostic tool orgy onto this like it's a cloned embryo of baby Jesus

Swap the a.c. And rsr relay ?

No parts swapping! Developing test procedures!