Baconsarnie Posted January 21, 2012 Share Posted January 21, 2012 Hi guys new to the forum so still learning, lol. Got a bit of a weird problem here. I fitted Japspeed decats about a week ago and everything was completely fine. (not sure if these are linked to the problem, thought I'd mention it). Part throttle driving, 1/4 throttle, 1/2 throttle pulling up the rev range there is no misfire. Full throttle, foot to the floor there is no misfire. But At about 3/4 throttle when pulling from around 2k rpm, as soon as it hits 3k rpm, I get a sudden splurt, jolt, misfire, but as soon as I pass 3k it's fine. It's mostly noticeable in 3rd. It's on 40k miles and due for a plug change, but surely if it was plugs it would happen all across the rev range. Also I have lambda sensor sims fitted to the decats which already have a spacer welded on them. I had a quick look under the car and the sensor wires are pretty low, and look like the may have rubbed on bumps but haven't jacked it up to have a proper look. Could this be a lambda sensor fault from possible wire scraping or does it sound like something else? Or are there issues with the stock map when fitting decats and not having a remap? The rest of the rev range it feels ok, maybe a bit down on power but that could be me being paranoid. Cheers guys Quote Link to comment Share on other sites More sharing options...
Neilp Posted January 21, 2012 Share Posted January 21, 2012 I spoke to somebody the other day about this with japspeed decats. The decats have bungs already installed and dont require the spacers as the also hit the ground. Dont have any info on the jolt but, what fuel are you using? Quote Link to comment Share on other sites More sharing options...
Baconsarnie Posted January 21, 2012 Author Share Posted January 21, 2012 95 regular. But Just filled right up with shell vpower incase it was a a fuel issue. Do these HAVE to be run on super? I thought uk models could accommodate 95 Ron? Quote Link to comment Share on other sites More sharing options...
Chris`I Posted January 21, 2012 Share Posted January 21, 2012 95 regular. But Just filled right up with shell vpower incase it was a a fuel issue. Do these HAVE to be run on super? I thought uk models could accommodate 95 Ron? It - HAS - to be run on Super (98RON in handbook/filler cap, but 97 is ok). You will be running the high det map and probably getting knock from 5k to redline, if not below when the knock sensor does not work. The knock sensor only works up to 5k RPM on the 350z. Hopefully you havent done any serious damage. Quote Link to comment Share on other sites More sharing options...
Baconsarnie Posted January 21, 2012 Author Share Posted January 21, 2012 I doubt serious damage has been caused. Is it a case of resetting the ECU for it to go back onto the proper map? If it on this high det map? Do these have 'eml flash when knock detected'? Quote Link to comment Share on other sites More sharing options...
Neilp Posted January 21, 2012 Share Posted January 21, 2012 95 regular. But Just filled right up with shell vpower incase it was a a fuel issue. Do these HAVE to be run on super? I thought uk models could accommodate 95 Ron? It - HAS - to be run on Super (98RON in handbook/filler cap, but 97 is ok). You will be running the high det map and probably getting knock from 5k to redline, if not below when the knock sensor does not work. The knock sensor only works up to 5k RPM on the 350z. Hopefully you havent done any serious damage. +1 especially with decats, breathing enhancements cause the car to run lean etc and can cause det/knock problems. A car should be remapped when being fitted with decats etc as the car will eventually revert the map back once it see's the afr's have altered. This results in absolutely no power gains until remapped with uprev. Running 95ron has shown severe engine failure as mark @ abbey found. The cars have no knock control after a certain amount of revs. Check abbey motorsports sub forum or search for this. Quote Link to comment Share on other sites More sharing options...
Baconsarnie Posted January 21, 2012 Author Share Posted January 21, 2012 So could this misfire be due to the map being reverted back for the dodgy afrs? Or could it be due to possible high resistance in the lamda sensor wires if they've possible scraped on the floor. Quote Link to comment Share on other sites More sharing options...
R35LEE Posted January 21, 2012 Share Posted January 21, 2012 95 is no good i'm afraid Quote Link to comment Share on other sites More sharing options...
Mark@Abbey m/s Posted January 21, 2012 Share Posted January 21, 2012 Do these have 'eml flash when knock detected'? Afraid not , running these cars on 95 octane fuel is false economy I feel. Quote Link to comment Share on other sites More sharing options...
Baconsarnie Posted January 21, 2012 Author Share Posted January 21, 2012 Do these have 'eml flash when knock detected'? Afraid not , running these cars on 95 octane fuel is false economy I feel. Have you got any ideas on the miss at 3k? Ecu need a reset? Lambda sensor? Spark/coil breakdown? Quote Link to comment Share on other sites More sharing options...
Mark@Abbey m/s Posted January 21, 2012 Share Posted January 21, 2012 If it is a hard misfire/cut out I would say it will be electrical, so maybe spark pplugs/coils or even crank trigger/ cam trigger problem or even a Air flow meter problem. I doubt that fitting De-cats will cause this problem thou. Where are you based? are you local to us @ Abbey? Quote Link to comment Share on other sites More sharing options...
Baconsarnie Posted January 21, 2012 Author Share Posted January 21, 2012 It's not a violent miss, nothing like a fuel cut where it feels like you're hitting a tree, lol, it's more of a splutter for literally a second, then carries on normal. Really confusing me how it's only at 3k??? Quote Link to comment Share on other sites More sharing options...
Mark@Abbey m/s Posted January 21, 2012 Share Posted January 21, 2012 sounds like a AFM problem to me. Quote Link to comment Share on other sites More sharing options...
Baconsarnie Posted January 21, 2012 Author Share Posted January 21, 2012 Any way of testing the afm? Where abouts are you based mate? As I'm interested in getting a remap, just want to get the inlet spacer before aswel. Quote Link to comment Share on other sites More sharing options...
M13KYF Posted January 21, 2012 Share Posted January 21, 2012 Any way of testing the afm? Where abouts are you based mate? As I'm interested in getting a remap, just want to get the inlet spacer before aswel. click on abbey's sig pic and it will take you to there website where you can find the address Quote Link to comment Share on other sites More sharing options...
Mark@Abbey m/s Posted January 21, 2012 Share Posted January 21, 2012 Yes the AFM can be checked using the Nissan Consult diagnostic machine, we are based just off of Junction 6 of the M25. Mark Quote Link to comment Share on other sites More sharing options...
Baconsarnie Posted January 21, 2012 Author Share Posted January 21, 2012 Ahh, that's not far at all!! I'll have to give you a call mid week to get booked in with you mate! (don't drive the car much, usually once or twice a week). Are there any checks I can do at home with a multimeter? Or are they all live tests rpm related so require a diag laptop and driving? Cheers for the help mate! Quote Link to comment Share on other sites More sharing options...
Baconsarnie Posted January 21, 2012 Author Share Posted January 21, 2012 Can Air flow meters be tested for flow via multimeter? Pin across the wires, blow into it, the voltage should change as it meters the air flow?? And a resistance test to check for a high resistance? Quote Link to comment Share on other sites More sharing options...
Mark@Abbey m/s Posted January 21, 2012 Share Posted January 21, 2012 Hi, Either use a scope and log the output from the AFM or use the Nissan consult again to datalog the air flow meter voltage Quote Link to comment Share on other sites More sharing options...
rm cya Posted January 22, 2012 Share Posted January 22, 2012 strange fault this one. weird how its only at 3Krpm. reminds me of my Evo, fitted new spark plugs, gap was too big, as soon as you come on boost, the boost blew the spark out causing a miss. but obviously theres no boost to blow out the spark on these could it not be spark plugs/coils breaking down as the engine gets loaded up? especially if its only a splutter? surely if it was the MAF, it would be jerking around all over the place and not just a miss at 3k as it can control the airflow? get under it and check your lambda sensor wires if it looks like theyve been rubbing. and remove your sims from the decats. i fitted the sims from zmanalex to my japspeed decats, then lowered the car, had a random look under the car to see how low the exhaust was and noticed the 02 sensors were really low. going to remove them on my days off, so im using the derv at the mo. Quote Link to comment Share on other sites More sharing options...
Mark@Abbey m/s Posted January 22, 2012 Share Posted January 22, 2012 strange fault this one. weird how its only at 3Krpm. reminds me of my Evo, fitted new spark plugs, gap was too big, as soon as you come on boost, the boost blew the spark out causing a miss. but obviously theres no boost to blow out the spark on these I doubt this will be a spark plug issues but I haven't seen or heard the problem myself, these cars just misfire on a cylinder all the time when the plugs are worn out or if the car has the wrong plugs fitted , we had a car in last week fitted with wrong plugs that caused a full cylinder misfire but this also caused a CEL for a misfire could it not be spark plugs/coils breaking down as the engine gets loaded up? especially if its only a splutter? surely if it was the MAF, it would be jerking around all over the place and not just a miss at 3k as it can control the airflow? We have seen cars with a stumble being caused by AFM , you can see this on the dyno the car was going ultra lean just before the stumble was felt get under it and check your lambda sensor wires if it looks like theyve been rubbing. and remove your sims from the decats. i fitted the sims from zmanalex to my japspeed decats, then lowered the car, had a random look under the car to see how low the exhaust was and noticed the 02 sensors were really low. going to remove them on my days off, so im using the derv at the mo. The post cat lambda's don't control fuelling at all they only measure the exhuast gas to tell the ECU if the cats are doing there job , that's why the cars throw CELS when removing the cats, its the pre cat lambda's that control the closed loop fuelling, you can disconnect the post cat lambda's and the car will run the same but just with a constant CEL up Quote Link to comment Share on other sites More sharing options...
Baconsarnie Posted January 23, 2012 Author Share Posted January 23, 2012 really appreciate all the help guys. Theres no CEL up nor does it flash as it splutters at 3k. how much is a AFM sensor? im wondering if its worth just chucking one on? is it just the sensor peice thats bolted into the intake pipe, or is it the casing aswel? cheers Quote Link to comment Share on other sites More sharing options...
R35LEE Posted January 23, 2012 Share Posted January 23, 2012 I have 3. £35 delivered each Quote Link to comment Share on other sites More sharing options...
Baconsarnie Posted January 23, 2012 Author Share Posted January 23, 2012 hi mate are they new? or used? also, is it just the sensor or the sensor with casing? Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted January 23, 2012 Share Posted January 23, 2012 Brand new here mate, with or without housing:thumbs: viewtopic.php?f=157&t=43466 viewtopic.php?f=157&t=43467 Alex Quote Link to comment Share on other sites More sharing options...
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