93' 850 Hard start, misfire, stall... MAF?

3uzfte · Post by **3uzfte** » 28 Dec 2010, 22:11

Hello MVS,
I am obviously a newbie, but have been around threads forever. I am trying to figure out this 1993' Volvo 840, w/ 2.4L 20v 5 speed, and can't for the life of me, figure out this stupid car. My friend called me about a week ago complaining the car tends to die when he comes to a light, and he must keep his foot in the gas to keep it running. I decided to pull the codes and sure enough it was the MAF, so I pulled it there was a crack in it. I also checked all of the intake ducting for cracks and vacuum leaks. So, I scavenged the local junk yards and found a S70 MAF, but didn't work, but wasn't really expecting it to. I ended up just buying a new 0280217002 Bosch MAF from a local European parts distributor. I installed it, but with similar results, start up, rough idle, and die if I don't hit the gas. If I do hit the gas, you can easily hear/see that it is misfiring, pretty good. So I figured he had a vacuum leak which obviously would screw up any results the MAF sensor was reading, so I decided to replace the intake manifold and throttle body gaskets, but to no avail. I tried clearing the codes with the battery being of for a few hours, but the MAF code comes back as well as the Cam position sensor, but I know that the CPS is brand new. I know the plugs were changed within the last 10k miles, along with the distributor cap and rotor, plugs wires are OE, but were fine before this whole episode. I decided to buy some MAF spray just to see if cleaning it might help, but I'm not very optimistic.

The car doesn't stay running, when it does run, it misfires badly than stalls, with a hard start, so it's hardly drivable. I pulled a 1-2-1 code, changed the MAF with a NEW Bosch, with the same part #, and visually look identical. I pulled the plastic intake tube between the MAF and TB, no cracks, tears, and clamps and connections are tight. I checked the IAC valve and it hums like it should before starting, and seems to adjust to try to keep motor running but can't keep it running with engine misfiring. I unplug the MAF, and it seems to be similar results, the car won't idle. The firing order is correct, and everything seems to be in working order. Because the original MAF is cracked, I don't have a known good one, I am still in the midst of trying to find one for cheap locally to try another one.

I can think of a few possibilities... A) The plugs are so fouled up that it's causing it to run like crap. B) Ignition coil is starting to fail/break-up. C) ECU is starting to fail or some wiring/electrical nightmare. D) The MAF sensor that I was given was faulty from the factory, which is possible, but not probable.

Any help or insight would be awesome. I did try to do a bit of research before I posted, but I am just stumped, flat out. I believe I am dealing with the Jetronic 3.2 ECU if it makes any difference. I am trying to get my friend back on the road, but working in 20* weather in front of his house isn't what I would call ideal, but am glad to help. Thanks again.

Post by **pkc303** » 28 Dec 2010, 22:25

Wow, what a bummer. I know you said the Camshaft Position Sensor is new, but I would check it anyway. Somewhere on the board is a test to check it.

Also, check here. https://www.matthewsvolvosite.com/forums ... f=1&t=1057

However, if the codes point to the MAF, it could be a vacuum line, which is where I would look.

Post by **boosted5cyl** » 29 Dec 2010, 07:37

Nice 240 BTW

Theres a plethora of things to check that I can think of, start by pulling the plugs though. If the MAF was marginal then it wouldnt take long to foul the plugs, especially in this weather. FWIW I bought a reman MAF sensor for our V70 at Oreillys and its been good for 15K miles and counting. Given a choice, yeah bosch would be a way to go, but its all about the money. I'm not sure where the cam sensor factors in on the running of this engine. Disconnect it, see what happens. Some ECUs will run without a cam sensor, some wont. Maybe oil has leaked past the cam seals and cludged up the new sensor.

Start with the simple stuff, fouled plugs after a MAF failre is very plausable. If the replacement MAF is faulty then it should run better (or at least differently) with it unplugged.

Am I correct in saying you had a MAF code, replaced MAF and the code for it went away?

Post by **jblackburn** » 29 Dec 2010, 07:48

If the cam sensor is throwing codes, there is something going on there. Get the wire for the sensor as far away from the ignition coil to distributor wire and see if matters improve any. The MAF code does not necessarily mean that the sensor is bad; it may just be confused about something. How is the condition of the hose from the sensor to the throttle body?

3uzfte · Post by **3uzfte** » 29 Dec 2010, 10:25

Hey, thanks for the replies. It sure is nice to have someone from St. Paul on here as well. Anyways, the story behind the CPS is that about a month ago my friends car just stopped on him, no spark, wouldn't start. If you waited a long time, like 5 hours, it would restart. I did my research and replaced the CPS, and it fixed it. But I never cleared the code, it just turned the light off, so I went on my way. Fast forward a month later, last week, my friend calls me and says that he is experiencing some idling issues and wants me to look at it. He drove it over to my house and I pulled the MAF to clean it and noticed that it was cracked. When I went to replace the broken MAF, it would start up, idle and die. I told him the deal, and that we would get one soon, I had no idea it was going to be this difficult. So I ended up just biting the bullet and buying a new Bosch from Carquest as EVERYONE said it was going to be special order, 3-5 business days. I put a V70 sensor in it, and it wouldn't even start. I put in the Bosch, and it ended up doing the same thing... Start-up, misfire, and stall. It seems as if there is random misfires that are very pronounced if I keep my foot in the gas and keep the R's around 3k, you can her it misfiring and bluish/black smoke coming out the tailpipe indicating a rich/unburned mixture. I decided to check the codes, and this time the MAF code went away, but now I'm getting a 314 and 324 on A6 which is CPS speratic signal or missing. Since the CPS was still brand new, I pulled it anyways and brought it back to Carquest for an exchange, replaced it, same symptoms, and same codes. I pulled the plugs, and sprayed them with carb cleaner, and through them back in and separated the plug wires so they wouldn't short out on each other. No luck. CEL comes back on, now I'm getting a (A2) 223 and 121 / (A6) 314 and 324 codes. I decided that everything seems to be working fine, I pulled the IAC and cleaned it, than decided to pull the intake manifold to check for vacuum leaks. Before I did, I pulled the Neg battery cable for about 4 hours, but after I put everything back together with brand new gaskets, I am still getting the same.... Start up... Misfire... IAC tries to catch it... Putter... Putter... Stall... Hard Start... Same thing, over and over... I check the plug wiring/firing order, and everything is good. Same codes keep coming back so obviously there's a problem... My last resort are these plugs... Also from my understanding is if I block off the IAC valve and try to start it by cracking the throttle plate, it should theortically take the IAC out of the equation as being part of the problem, right? Obiously if the IAC isn't able to suck air in, it isn't likely having an effect on the air flow after the MAF. I would think the MAF is ok, especially if it can keep a somewhat limping/misfiring motor running for at least 5-10 seconds.

Today, I am going to try take a bit of sand paper to the plugs to see if I can crap if the plugs, I know I need to hit um with air before I put them back in.... The plugs, other than being carboned up, look fine, maybe I need to soak them in gas for a bit instead. I also decided to buy some MAF cleaner and figured I would give it a shot, but haven't made it over to his house yet to see if it will do the trick, but in reality, it's a brand new MAF it shouldn't have any oil residue on it.

Thoughts please, I will update you guys if the plugs or the MAF spray works, I need help, and I am about at my wits end.

Post by **boosted5cyl** » 29 Dec 2010, 11:47

Dont sand the plugs or wirebrush them or dip them in gas or anything like that. If you insist on using a solvent, use starting fluid (ether). The best way to clean them is with a propane torch. Once the plug gets into its correct temp range it is self-cleaning. You will see it turn to the grey that you usually see and a good running motor. That said, you could get some $1.5 copper plugs and just swap em out. Be sure to gap them.

You theory on the IAC being blocked off seems sound, give that a go. Check the cam belt\pulley timing too. If it hopped a tooth or two it would explain the CPS code as well as the crappy running.

How about electrics? I know you said you checked the wires, but is the battery plenty strong? Resistance in the HT coil good?

I think my process from here would be to througly clean (ideally replace) the spark plugs, check the can timing, unplug the maf, block the IAC start it up and go from there. Also a faulty coolant temp sensor could have lead you down the path to fouled plugs, might be worth checking that it works too.

Oh O'reillys up my way have been awesome for Volvo parts. Usually if they didnt have it in stock they would be able to get it later that day..

3uzfte · Post by **3uzfte** » 29 Dec 2010, 15:14

Well, thanks again guys for the advice. I actually have had some luck. I've been cleaning plugs with sandpaper and gasoline for a long time, in some shops they even have sandblasting machines for plugs. Anyways, I got them plugs pretty clean, man were they nasty.... I tightened everything down, and sure enough I start it up with the same results, but this time is managed to stay idling for about 10-15 seconds, than shut off. I than cleared all the previous codes, and started it up and this time it stayed running for about 15 seconds, with no issues, smooth idle, but than slowly lost R's and died. I started it back up and noticed the CEL was back on. I pulled the code, and again I got the (A2) 1-2-1 code, but I wasn't getting the other codes anymore. I went over and unplugged the MAF, and I'll be... it starts up and idles like a dream, no misfiring, and rev's perfectly throughout the range, however it stumbles a bit, but that's like because it's in limp in. However, even with the MAF unplug, I still can't get it to idle on it's own for the life of me. I can drive it, it is roadworthy, it just needs to be kept going with a touch of the gas pedal. I can keep the motor running, but if, as as soon as I plug in the MAF, it chugs, misfires, and dies.

My thoughts go as follow... His car was running ok, or so he thought. In reality, he was driving with 1) a cracked MAF sensor, 2) a sticking idle air control valve, and 3) a slight vacuum leak at the intake manifold. All of these things combined to provide a perfect storm if you will, which cause a bit of difficulty try to create an easy diagnosis. After did all of the previous stuff, it wouldn't stay running even with the MAF unplugged, but that's obviously due to dirty, fouled up plugs, which he had likely been driving around on for quite some time. Now that I have gotten the plugs clean, and can eliminate the MAF sensor, I can keep the car running just fine, until I let off the gas and try to let the IAC motor control the idle speed. It seems to idle fine, but than it seems to stick, and than it just dies, and usually creates a little fuss turning over, but always starts. If I plug in the new Bosch sensor, it stumbles, and stalls, if I plug in the cracked one, it seems to start up and idle for 2 seconds, than die. If I plug in the V70 MAF, it turns over, and builds compression, but won't even start.

I talked to Carquest, and they are going to order me a replacement MAF that will be here in the AM. I am also going to UPullRParts and see if I can score a super cheap IAC to see if I can swap it out for a different one. I attached a picture of the new Bosch sensor, it's like it got bumped or installed funny...

3uzfte · Post by **3uzfte** » 31 Dec 2010, 13:58

You guys are pretty good. I ended up getting a faulty Bosch MAF from the parts place, but replaced it with no questions asked. I also managed to score 2 IACs from the local UPull yard, both for $20. After cleaning the plugs, replacing the MAF and IAC, it started right up with no issues. I got my friend back on the road. During this time, I managed to clean up the TB, intake hose, as well as I replaced the intake manifold and throttle body gaskets, injector o-rings, as well as a few things here and there to clean up this greasy nasty mess. Thanks again for all of your help.

Post by **boosted5cyl** » 03 Jan 2011, 10:56

Glad you got it sorted....