Misfire with AC on | Ford Escort Owners Association (FEOA)
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Misfire with AC on

Discussion in 'ZX2 1998-2004 2.0L DOHC' started by RonW, Oct 17, 2020.

  1. RonW

    RonW FEOA Member

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    Okay So I'm on my 4th ZX2, so I'm pretty familiar. This has me stumped.
    2000 ZX2, 105k 5spd manual, all the goodies available, including pita ABS.
    Car ran great for 10k when purchasing. Had a plugged heater core. Was summer so I ignored it for the time being. Mistake #1. I replaced timing belt with pulleys, did wires, coil, plugs, all Motorcraft. All back together, car ran flawless for 4k more. On a long drive on a Hot summer day and the last 4 miles of the trip during a downshift the Serp belt started shredding. I made it home with a few cords hanging on and had a spare belt in trunk to swap it. Drove the car back to work and popped the hood. Heard some bubbles in radiator overflow tank. Uh oh, I thought for sure head gasket. I opened the radiator cap (for the first time) after cooled and found a mess of what I can only assume was a sealant added before purchasing. I was going to do a flush during summer anyway for the heater core, so did that with a heater core backflush. Did not have access to a head gasket bubbler, so a compression test yielded no issue, clean oil. So flush done and back to drive. Heater core still not working, tiny bit better but not good at all. Drove it home. Next day all hell started to happen. Three weeks later and a mess of O2 issues and phantom readouts from any tech I could find and I found the problem. Leaking heater core shorted a plug under ECU, power forced into O2 upstream. Took the shorted heavy power wire out of connector, soldered and capped then heat shrink, MAF cleaner and compressed air to the connector and plugged it back in. New O2, new ECU reprogrammed to my car, new heater core. Closed up and voila, car runs good again.

    Now one issue, sitting at idle the car gets very hot, 228 kind of hot, 180 tstat. Fan kicks on but still it gets to hot. I replaced radiator, same. Got a head gasket bubbler and after 4 tests, cool, hot, whatever I could think. Nothing, fluid stays blue. Antifreeze is clean, oil is clean. It did not get hot before all of this. What happens is two things.

    #1 - when it gets so hot ,at a stop light when I start to go it has this hesitation and seems mild misfire, never any codes.

    #2 - when ac or heat related ac settings are used the fan kicks in and the car never gets above 185. However it hesitates and mild misfire with AC on at every take off.

    It's very annoying and I'm at the point of pulling the head off just because. Something I'd prefer to avoid. Any help or suggestions would be great. New member and hoping I'm in the right place.
  2. Swift

    Swift FEOA Donator

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    Replaced rad, what about thermostat? I had one go bad after 10k.
  3. RonW

    RonW FEOA Member

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    Yes, I actually changed it from a new 195 to a 180 in hopes of reducing that high heat issue. I'm wondering if I should revisit the shorted wire and reclean all the ends up better?
  4. Apex

    Apex FEOA Member

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    Get one of those block tester kits that uses blue fluid and tests for exhaust gas in the cooling system before you go straight for the headgasket.

    Are you absolutely certain that your fan is kicking on when you're getting above a certain temp? If you're not overheating when you have the AC on that sounds to me like your fan is only kicking on due to the AC calling for the fan to be on. This should be easy to test, I would keep the hood popped but closed so you're not letting the heat escape and see if the fan kicks on when you're getting too hot.

    You could also check what the ECU sees the coolant temp at when with an OBD2 reader that can see live data, if it's not seeing the temperature, check the wiring going to the coolant temp sensor (there are two of them, one for the ECU, one for the gauge cluster).

    Figure out why you're overheating before you start replacing things, it will save you a lot of time and money.

    As for the misfire, where did you get your motorcraft stuff from? Unfortunately Amazon is known for having counterfeit motorcraft spark plugs. You might suspect those if that's where you got them from. Even if not, examine the porcelain very carefully for any microcracks, they may not short all the time which can give you a real headache trying to test them.

    Otherwise, need more data on the misfire to even have a clue where you might start, FORScan would be an excellent tool to use, check this thread for recommendations on a scanner. https://www.feoa.net/threads/fuel-pressure.116022/#post-1111130 Note that madmatt2024 gave a cheaper option on an adapter than I did.
  5. RonW

    RonW FEOA Member

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    Thank you so much for the detailed reply. So I have a head gasket tester, blue fluid type, I tested it 4 times, all clean so no exhaust in radiator. I also have forscan and use it to monitor all the time. I also have Torque pro and another that monitors everything including $06 stuff. Fan will kick on at 228 with AC off, I've changed the ECT twice, though never paid much attention to the connector? The temp seems to be on point according to all three apps. It's very odd because it stays very cool when driving under most any condition, only long stops at red lights will drive temp up.

    I'm thinking maybe the AC compressor is going internally? It works fine and is full and functional. Also 99% of my parts come from Rock auto and look legit. I just replaced IAC valve as I knew the incorrect until was on the car but it really made little difference.

    The main reason I'm considering the head gasket is really to cleanout the coolant areas. I'm concerned that the sealer that was used clogged something up?

    I hope I gave all the information? I really appreciate any input as I'm not super crazy about pulling the head when I'm sure the gasket is sealed. Not a fun job on this engine.

    Thank you
  6. Apex

    Apex FEOA Member

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    That seems really high for it to be kicking on at 228, do our fans have two speeds? I'll check my wiring diagrams tonight. It's possible that the low speed isn't working and only the high speed works with AC on and when you're hitting really hot temps. It seems to me that the issue isn't related to the head gasket or AC system since having the AC on (meaning the fan is guaranteed to be on) causes the car not to overheat.

    There should be some bidirectional controls to turn on the fans, right? That would probably be where I would start, if there's two speeds check that they both work.

    You could unbolt the clutch on the AC compressor, just make sure to keep track of any shims that come out. This way everything still works electrically, you just won't be spinning the compressor itself. This isn't a great solution but this would at least let you start isolating the problem. You could also spin the compressor by spinning the clutch by hand and see if there's any major resistance.

    On my ZX2 the pulley somehow sheared into two pieces and was occasionally spinning the compressor even with the AC system off. This would cause a crazy noise and kind of made it seem like the engine was running rough. Doubt this is your issue, but I didn't notice it until I looked in the engine bay while it was happening and noticed the clutch sometimes spinning when the pulley would catch it just right.

    Also, have you checked mode 6 or live data for which cylinder is misfiring when it's running rough?
  7. RonW

    RonW FEOA Member

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    So that is a great question, I thought there is supposed to be two speeds, low and high, and I really dont think or know if the low speed fan is working? I have replaced the PCM module or CCRM if you want, and the ECU for the leaking heater core issue. I dont know if there is another relay or something for the low speed side of fan? Also I've changed water pump recently so that can be ruled out as well. Its so odd that all of this stuff began with a semi broken serp belt, prior to that all was well... I have checked mode 6 and its random at best, the codes are a bit confusing and i dont understand the concept as I can see $53 $00 failed and in the next line the same number or MID-CID will show as passed? also showing codes which dont pertain to my vehicle add to the confusion as CID $07 is a cylinder 7 code but obviously no Cyl 7 exists. I do have a spare AC compressor that I know to be good and will eventually swap it out to see, but with winter upon us it is not critical. The overheating issue is, I'm unsure if I should continually flush the system? I installed one of those prestone hose connectors to connect a hose to it and did a few fresh water flushes. If I wasnt sure that I took every precaution I know of, that this is a trapped bubble in the system, If so then I'm lost as to how to get it out. I ran the car with a funnel in rad and heat blowing with coolant above the funnel for 20 mins or so, all bubbling seemed to stop. This was done each time I flushed and refilled, which total is maybe 6-8 times.

    I really appreciate the help, I'm confident we will stumble upon the problem as this site has always helped me, albeit as an observer until now. I'm happy to give back and will be looking to help others where I can as well. Thanks all
  8. Apex

    Apex FEOA Member

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    I think we are dealing with two separate issues.

    Like I said, I don't suspect there is an actual problem with the AC Compressor, but it would put extra load on your engine potentially showing a problem you don't usually see when driving it around.

    Unfortunately I didn't get a chance to look at my factory service manual for the wiring diagrams, so I'm looking at Alldata right now. According to Alldata $53 appears to be cylinder-specific misfire counter as a percentage. Might fail if it's exceeding the point where your catalytic converter will get damaged if I am understanding it correctly.

    I haven't messed with mode 6 much, so I don't remember exactly what all of the data you should be looking at would be. There should be PIDs for cylinder misfire counters where you can watch each cylinder count up to 200 times or something like that. Did you ever check to see if the car misfires under heavy load without the AC on? Or, can you get it to misfire when you have the car sitting with the AC on and free revving it?


    As for the fan, according to Alldata there is indeed a low speed and high speed on the fan. There's a few ways you could approach this to test to make sure that you're getting power to the low speed on the fan. It could be the CCRM has a bad LFC relay, the pin on the CCRM that powers the low speed on the fan is loose, the wire that gives power to the low speed connector on the fan is broken, or the fan low speed winding is broken. There are probably other possibilities I'm not thinking of, but my point is that you should check all these possibilities and figure out why this is happening.

    I don't think you have any bubbles or any other issues with the cooling system, but the best way to make sure a cooling system is bubble free is to do it with vacuum, if you have an air compressor there are a couple of tools for this where you can extract all the coolant as well as put it under vacuum and fill it with coolant with no air existing in the system to begin with. I don't think this is the problem though if the engine is seeing the correct temperatures. You could also test your radiator cap to make sure it's keeping the system under the correct pressure, but again I think your cooling system is working fine, it's just the low speed on your fan isn't working.
  9. RonW

    RonW FEOA Member

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    The misfire always stays under the threshold so it's hard to get a handle on it, also I cannot repeat it under any condition except takeoff from a dead stop, it does do it in a more mild way with AC off but temp at 228 and fan blowing, it's also not constant, clears up once under way and will not happen at a rolling stop.

    I agree we have two issues, I made a test wire with an old terminal I have from another car I stripped down for parts, I'm going to try the fan first on high and low. I have a donor fan also that looks a lot worse shape but does work fine should that be the issue? I'm kinda convinced that I need to get this low side fan working first and move from there. I'm also going back to my initial problem of the shorted wire, as that issue was forcing 12v into the O2 sensor causing the fan to go on when I shut car off and all kinds of craziness. It may have damaged the fan itself, or wiring, or maybe in that original connector there is another damaged wire I overlooked?

    I'm just learning more about $06 and I'd love to have never had to. It's confusing at it's best unless you have a complete diagnostic chart that goes to your car in front of you, which I do not.

    I'm just curious if I never noticed the low fan coming on before all of this happened? I honestly don't remember either fan coming on and the engine ran cool. Could be the low fan was coming on and I just don't know.

    Starting with the fan, the misfire issue may be associated with the heat of the engine and exacerbated with AC on?

    Will post my findings, also new Rad cap, tried several as I have donor cars... thanks so much again!
  10. Apex

    Apex FEOA Member

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    It's definitely possible, but I agree that you should fix the low speed fan issue then go from there so that it eliminates the possibility of the two issues being related.
  11. RonW

    RonW FEOA Member

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    Well I checked the fan and both high and low work fine with direct power. I also switched out the ccrm just because I had one with which to do it. And it is not the ccrm, or the fan motor. That means I need to see if it's a wire or if for some reason it's not calling for the low speed to kick on?

    Drove it home tonight and sitting in traffic it got up to 211 degrees from a cruising temp of 174-181. It's making me crazy of why it climbs so high so quickly?? I'm assuming at the moment that 211 should have kicked on the low fan but I could be wrong? Also when I switched out the ccrm I let it sit there and idle, hood closed and it never went above 181... so confused
  12. Apex

    Apex FEOA Member

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    Are you able to see the PIDs for the cooling fan when it is on? I believe there are two of them for low speed and two for high speed. There should also be some bidirectional controls to turn on the low speed fan and you could check for power when you command it on.

    It's entirely possible that both CCRMs are bad, though unlikely. I would test for power coming off the CCRM for low speed power to the fan when you command it on (or if the fan turns on, since it worked fine with direct power).
  13. RonW

    RonW FEOA Member

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    I'm going to check for power to the low side of fan. I need to investigate if the app(s) I currently have can perform some of the items you mentioned, I haven't gone that far into any of them yet. If not I have a newer snap-on unit at work I can use. It is possible that both ccrm are bad, however the one that I just took out was purchased not long ago from a reputable recycler of used parts that claims all units are checked for 100% working condition. Not that it means much, but it's something. At least I'm narrowing the possibilities.

    Still bothers me that it rises so quickly, it's what keeps bringing me back to a blocked passage somewhere...

    Anyway that's tomorrows problem for now. Thanks again for the help, it's really great to bounce these things off of others
  14. RonW

    RonW FEOA Member

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    Okay so problem 1a of issue 1 is resolved! The ccrm did have an issue, either that or a bad pin connection to the low fan power. As of now the low fan is working. Kicks in at 217 and high speed kicks in at 228 so that part of the issue (overheating) is done.

    The root of the problem, overheating in the first place is still there. I don't believe this car in this scenario should get to 217 degrees. It's relatively cool, highs on a hot day in low 70's, IAT gets to 90 at a standing light.

    I'm going to flush again and then do another head gasket test for kicks.

    Now here is what I'm noticing. The ghost / random misfire only happens when the engine gets that hot, 210+, AC on makes it more noticeable. The misfire is more of a drag or lack of power, where it feels like it's bogging down off the start, first gear most noticeable, second gear sorta clears up, then it's fine. Couple of additional things, if I were to guess I'd say it's getting to much fuel, when my shorted wire happened fuel trims were all over the map, they seem relatively normal now. I'm not sure what notifies the load condition but watching the load percentage it seems to be high at times when I feel it shouldn't be, like in the upper 80's when it is not being pushed or revved to any extreme.

    I have in the recent past cleaned the injectors, throttle body, and replaced fuel filter, however these were done 2 months prior to any problems arising. I will also say my gas mileage is not what it was, seems to be using a good 20% more fuel than before.

    Okay hopefully that sheds some more light and rings a bell with someone. I will update after flush.

    Thanks
  15. Apex

    Apex FEOA Member

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    What do your fuel trims (short term and long term) look like on and off idle? Is there a difference when it's starting to run hot?
  16. RonW

    RonW FEOA Member

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    They usually bounce around between -2 +2 at idle hot and cold. During heavier acceleration they will climb up to +30ish and back down to a back and forth of between 2-5 both + and -

    I've thought about the possibility of the Cat being bad? But I have nothing really to go by on that, it runs fine other than this issue and flies thru emissions.
  17. RonW

    RonW FEOA Member

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    Both O2 sensors have been replaced multiple times, due to the shorted wire.
  18. Apex

    Apex FEOA Member

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    I'm not suspecting that the sensor is bad, there's a lot of factors that affect fuel trims.
  19. RonW

    RonW FEOA Member

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    I'm all ears about what I may have missed. I've actually compared it to another 2000 zx2 that I own and it seems pretty consistent as far as fuel trims go. The other car, an automatic, seems to stay below 30 on those hard push to get on the highway on a hill. I don't know enough about what affects them to give a good answer
  20. Apex

    Apex FEOA Member

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    Your total fuel trim should always be as close to 0 as possible, not positive or negative. 30 is an extremely lean condition where the car is responding to the o2 sensor seeing a leaner air fuel ratio, the ECU responds to this by injecting 30% more fuel.

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