only running on 3 cylinders?

99_xc70 · Post by **99_xc70** » 13 Dec 2011, 14:59

I finally got my 99 v70xc running but on cylinder 1 and 2 it's either not getting spark or fuel? I pulled the plugs out and they were black but not fuel soaked. They are new so I cleaned all five and reinstalled, still no difference.

I swapped all plugs around and still have a misfire on cylinder 1 and 2. So now I've swapped coils, plugs and injectors and still have cylinder 1 and 2 that seem to not being doing anything while running and I uplug either the coil or injector. On 3,4 and 5, I unplug either coil or injector and the engine almost stalls out(normal). I figured compression, so I checked and I have pretty decent numbers from 190-200psi. What else could it be? Fuel pressure is also above 50psi while running. I held a tire pressure gauge at the end of the rail while running and it only goes to 50psi so it could be higher.

Post by **rspi** » 13 Dec 2011, 16:04

Check the coil wires to make sure they are not backing out of the connectors. Also, make sure those injectors are getting a paulse with an injector tester. Maybe you have a problem with the fuel injector relay.

99_xc70 · Post by **99_xc70** » 13 Dec 2011, 16:33

I did check the injector with a noid light and they do pulse. I also check with my meter and they are getting 12 volts. The injector relay, is that the big red one or is that the fuel pump relay? What would cause just 1 and 2 cylinder to be not working properly? Cam sensor, crank sensor?

Post by **misha** » 13 Dec 2011, 16:52

99_xc70 wrote:...The injector relay, is that the big red one or is that the fuel pump relay?

No,it's the grey one located at the fan shraud/carrier.

I hate to say this,but this could be a time for compression test.

99_xc70 · Post by **99_xc70** » 13 Dec 2011, 17:53

I did a compression test pretty much right away. Removed all plugs, unplugged all injectors and coils, foot on the gas pedal to the floor and cranked each cylinder over about 5-6 times and got 200-190psi from cylinder 1-5.

The relays on my 99 v70xc on the fan shraud are just for the fans or no? I think the 850 has a injector relay there but not the later 99 xc? I have another good running car to swap parts from but I thinks those relays on my car are just for the fan.

Post by **misha** » 13 Dec 2011, 18:26

I don't know...i see that compression results are ok.

Fuel pressure shouldn't be more than 43.5psi at first prime without starting the engine.
At idle it should be around 30-35psi and again at WOT(wide open throttle)in high rpm's it should be 43.5psi again.

The only thing which is falling on my mind would be a bad cap & rotor.

Are the spark plugs OEM Volvo?

Maybe the injectors are bad.

Is the CEL on?Are there any codes stored or pending?

Post by **jblackburn** » 13 Dec 2011, 18:40

99's have a different fuel management system. ~50 PSI is right.

They also don't have distributors.

I just can't think of why a 99 would be disabling those 2 cylinders UNLESS it's something where the insulation has come off in the wiring harness or something of the sort.

Have you removed the plug and grounded it to the head while the engine is running to confirm it is not actually sparking?

99_xc70 · Post by **99_xc70** » 13 Dec 2011, 19:43

I removed #1 plug and ground it to the head and got my friend to roll it over, I have spark and the fuel injector connector with a noid light while cranking is pulsing. On both 1 and 2 cylinders. Just plug everything back in and start it up runs ok just has a slight misfire.

I put my foot on the brake and put it into drive and it just start banging and shaking, put it in neutral and it smooths right out but still has a slight misfire, same when in reverse, banging and shaking while my foot is on the brake. It's only under load that it starts bucking, banging, popping, backfiring. While in park and idling I can unplug 1 and 2 injector and it almost runs better but if I do that to 3,4, and 5 injector it almost stalls, same with unplugging each coil, no change on 1 and 2.

I bought the car not running. The previous owner drove the car to some shop for a rear brake noise, left it and got a call asking "how do you start the car". They ended up burning the starter up trying to get it to go. I bought the car and towed it to my work, replaced the starter and ended up finding no fuel pressure, repaired the broken fuel pump and now it runs but runs like this. They installed new NGK plugs? Good? I read somewhere about reseting the ecu? I'm lost at what to do next.

99_xc70 · Post by **99_xc70** » 15 Dec 2011, 04:17

What about the cam or crank sensor? They control cylinder timing, how do they work? I've tested the crank sensor just by unplugging it and checking with my meter and got 177.5ohms? Normal?

Post by **Ozark Lee** » 15 Dec 2011, 05:31

A bad cam or crank sensor would keep the car from running at all, not just on 2 cylinders.

With all of the diagnostic work you have done I think you have pretty much narrowed things down to clogged injectors on cylinders 1 and 2. You can often detect a clogged injector with a long screwdriver to act as a mechanics stethoscope. Put the screwdriver on the injector and then put your ear up to the screwdriver handle.

Compare the sound on the cylinders that are running to cylinders 1 and 2. A good, clean, injector will have a crisp click whereas a clogged injector will sound comparatively dull. I have had some luck reviving clogged injectors with carb cleaner but to do it really right they should be ultrasonically cleaned.

...Lee