Cylinder 1 Misfire and Oil on Plugs

Johnny78Blaze · Post by **Johnny78Blaze** » 27 Nov 2011, 21:11

I forgot I have a test light probe to check for positive and ground currents. I checked all the connectors and they all have a strong positive current and a faint ground current. I read somewhere that I should unplug the ignition coil wire and have someone crank the engine while probing for the ground current. Apparently it's supposed to pulsate while cranked. I didn't have a helper but will check that tomorrow. I'm assuming that if there is no pulsation in the ground current to the injectors, that maybe there is damage to the wiring or a possible issue with the ECU. Does that sound right? I don't think the diaphragm in the FPR is ruptured or I'd have gas in the vacuum line. This sound right as well? Could my problem be a bad relay? I'll get back to you guys tomorrow.

Post by **Ozark Lee** » 28 Nov 2011, 13:03

The master fuel system relay (it is a gray relay on the fan shroud) provides power to the fuel injectors but it provides power to all of them. A problem there wouldn't be limited to just a 1 cylinder misfire.

The way the fuel injectors work is that the master fuel system relay provides battery voltage to all injectors simultaneously and then the ECU pulses the injectors by pulsing them to ground. We have had rare occasions where the edge connector on the ECU has caused problems if you are not seeing a pulse on the electrical line. Cleaning the connector and spraying the ECU socket with contact cleaner has fixed those problems in most cases.

...Lee

Johnny78Blaze · Post by **Johnny78Blaze** » 28 Nov 2011, 15:07

There's a pulse on all 5 connectors. My fuel pressure kit showed up a day early and I made time to use it. Relieved fuel pressure by disconnecting fuel pump and running the gas out the car as directed in Haynes. Hooked the tester up to the fuel rail and got astronomical results compared to specs in Haynes. Haynes says 4.39 psi and I was up over 40 psi. It appeared that the stem on the fuel rail's Schrader valve is bent and moves around however the hell it wants. I don't know if this affected the test or not but I can't imagine that this is the culprit. I'm at a loss of words right now and it's dark, so I don't have an opportunity to hook the fuel tester up to anything else. Next step should be where? Should I check the pump next? If the car is running rich, that would make sense because my mpg has gone down since before this thread started. Sounds like this could be causing misfires as well. I know my exhaust sounds like crap right now with the engine misfiring. I hope there's no cat damage because of all of this. Suggestions please...

Johnny78Blaze · Post by **Johnny78Blaze** » 28 Nov 2011, 15:29

Meanwhile, back at the ranch...

Just read online that fuel pressure should be 43.5 psi. That sounds about right as far as my test went. I didn't bother starting the car because I felt my pressure was already through the roof according to Haynes. Wth is up with Haynes anyway? Book is becoming more bothersome than helpful. My pressure jumps up very quickly. Almost instantaneously to ~45 psi. I'm going to check and see if the regulator is open at the return side and the vacuum port. I read that if both are open, then I need a new regulator. Update in a few minutes.

Johnny78Blaze · Post by **Johnny78Blaze** » 28 Nov 2011, 16:09

Here's the link I've been reading...

www.volvoclub.org.uk/tech/service/850/BasicTesting-Turbo.pdf

I connected my fuel pressure tester right to the rail at the Schrader valve (driver side). Jumped very fast to proper pressure specs. I tried blowing in the return port of the FPR and also the vacuum port. Neither is open. According to the link, I should replace the FPR because my pressure jumped so fast to spec. At least that's what I think I'm reading. If that's the case, I'm going to hit the salvage yard up again and grab parts from the same Volvo I got my other parts from. I'll grab the fuel rail and regulator together. I don't know what else to do at this point. Those are my plans unless someone has a better suggestion(s). I'll recheck the pressure after I put the 'newer' rail and regulator in. It could be awhile before I get to the salvage yard. Hopefully before Xmas...

Post by **Ozark Lee** » 28 Nov 2011, 18:50

Johnny78Blaze wrote:There's a pulse on all 5 connectors. My fuel pressure kit showed up a day early and I made time to use it. Relieved fuel pressure by disconnecting fuel pump and running the gas out the car as directed in Haynes. Hooked the tester up to the fuel rail and got astronomical results compared to specs in Haynes. Haynes says 4.39 psi and I was up over 40 psi. It appeared that the stem on the fuel rail's Schrader valve is bent and moves around however the hell it wants. I don't know if this affected the test or not but I can't imagine that this is the culprit. I'm at a loss of words right now and it's dark, so I don't have an opportunity to hook the fuel tester up to anything else. Next step should be where? Should I check the pump next? If the car is running rich, that would make sense because my mpg has gone down since before this thread started. Sounds like this could be causing misfires as well. I know my exhaust sounds like crap right now with the engine misfiring. I hope there's no cat damage because of all of this. Suggestions please...

That is one of many glaring errors in the Haynes manual. The other - more significant - one is that they have the spark plug wires wrong on the distributor cap. As bad as the Haynes is it is the best one out there when compared to the Chiltons manual. Between a Hanyes manual and the factory service manual hosted here you can pretty much figure out anything on these cars. A VADIS disk helps out a ton as well with exploded drawings and part numbers. We also host all of the electrical drawings but they are a bit of a mess due to the way they were originally scanned.

...Lee

Johnny78Blaze · Post by **Johnny78Blaze** » 28 Nov 2011, 20:05

It's been posted elsewhere about how hard it is to hook a fuel pressure tester up to an 850 fuel rail. When I did it earlier I removed 2 bolts from the throttle mount and loosened the third so I could slide the throttle mount over and access the fuel rail's Schrader valve easier. I haven't tested while the engine is running but I know I'm losing significant fuel pressure according to the gauge earlier this evening. Testing the fuel pressure again tomorrow, this time with the engine running as well to monitor the pressure. The factory service manual hosted on this site says to hook the pressure tester between the fuel line and fuel rail. Guess it's worth a shot if I can figure out the easiest way to do it. My gut says fuel pressure regulator but I haven't worked on issues like this before. Stay tuned.....

Post by **Ozark Lee** » 28 Nov 2011, 22:27

Hook the fuel pressure gauge on the end of the fuel rail - that will tell you what you need to know. Also monitor the pressure after you turn the car off. It should not fall off rapidly. The other tests in the factory service manual actually involve crimping the fuel return line as I recall but that should be done with caution as the pressure can rapidly get high enough to damage other stuff.

...Lee

Johnny78Blaze · Post by **Johnny78Blaze** » 29 Nov 2011, 06:56

Ok thanks Lee. I'll give it a shot this afternoon and post my results.

Johnny78Blaze · Post by **Johnny78Blaze** » 02 Dec 2011, 17:53

Went to the salvage yard and grabbed a fuel rail and FPR. Wrong ones.....DOH! Can't get another until next week. @#$^@#@!

Cylinder 1 Misfire and Oil on Plugs

Re: Cylinder 1 Misfire and Oil on Plugs