Brucey 95wrx Posted September 10, 2019 Share Posted September 10, 2019 My car is juddering and back firing at 4000 rpm just before the turbo kicks in after having head gaskets replaces so far I have changed fuel filter new plugs new coil packs green label maf turbo is brand new swapped injectors with spares still the fault persists but no check engine light It even stops at 4000 stationary and starts popping and banging Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted September 10, 2019 Share Posted September 10, 2019 Is it definitely firing on all cylinders, plugs all same colour ,none of the plugs flooded? Sounds like a misfire , I wired the coilpacks back to front on 1 bank b4 🤐 Had the same symptoms, surprised it run on 2 cylinders at all tbh 🙄. Try checking engine loom earths /breaks in the insulation on the loom and injector/coilpack plugs .failing that a compression test and check the timing Mark's 1 Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 Deffo firing on all 4 driving it around town up to 4000 rpm you would not suspect a fault at all sounds good ticks over ok plugs are all a great colour it’s almost as if it is hitting a limiter at 4000 and shutting down the ignition timing which is causing backfire compression was at 169 psi on all cylinders before the head gasket was replaced with the throttle closed Quote Link to comment Share on other sites More sharing options...
Tidgy Posted September 11, 2019 Share Posted September 11, 2019 Is it the right thickeness headgasket? has it stuffed up the comrpession? can you get it on a dyno and diagnose whats going on? Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted September 11, 2019 Share Posted September 11, 2019 Your supposed to check compression with the throttle "jacked open " ,although those figures seem good have you checked compression since doing the headgaskets? If the timing Mark's are out it could cause it to cut ignition at high rpm/load , due to crank n cam sensor readings. Are the plugs the right heat type (heat 6 for standard,heat 7 for mapped) are gapped correctly ? Have you done a self code check or just think theres no codes due to not having a eml ? Maybe a code check and ECU reset might help ,along with checking vac lines from inlet ,turbo and fuel pressure regulator too Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 The gasket put on was a 1.4mm mls I need to re check the compression but I have no valve tolerance at all is this right with the hydraulic cups? Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 I have iridium heat 7 as running around 330 bhp on a chipped z4 ecu they are gapped at 0.6 i have plugged the black connectors in and the engine light just stays on no flashes I have disconnected the Battery and left over night to reset ecu but still it persists is there anyway I can upload a video? Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted September 11, 2019 Share Posted September 11, 2019 There's supposed to clearance for the hydraulic valves , compression readings would probably give you a idea if a valve has positive pressure at cam base circle . Causing a Valve to be jacked open with constant pressure from the cam . If compression is down , it's very difficult to test valve clearance with the engine in stitu . So just checking that you can turn the lash caps with your fingers (when the cams at base circle) is a easy way to see if the cams are creating constant pressure on a lash cap (causing the valve to stay open) Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 Only 2 of the 8 on passenger head would twist but how do you adjust these? Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 I did have valves reseated while heads were off Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted September 11, 2019 Share Posted September 11, 2019 If engines still plumbed in , just do a compression check. It should let you know if the valves are seating correctly. 2 main options for clearance adjustment. Measure the clearances with feelers gauge and buy lash caps that are the correct size (about £30 per lash cap) I always get the engineer to "tip the valves" ,to take the same amount of material from the tip of the valve , as what he takes off the valve seat when machining the valve seat faces Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 What are lash caps sorry complete novice Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted September 11, 2019 Share Posted September 11, 2019 17 minutes ago, Brucey 95wrx said: Only 2 of the 8 on passenger head would twist but how do you adjust these? Was that with the cams at base circle ? Cam lobe should be facing upwards and away from each lash cap so there should be no pressure on each lash cap (have to rotate the cam to check each one) Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted September 11, 2019 Share Posted September 11, 2019 Soz bud , people call em different things. The hydraulic lifter cap that has a shim attached underneath , cam lashes onto it to push the valve . The shims are non removable on most ej's ,so you have to buy a complete lash cap /lifter to get the correct size shim , to adjust valve clearances Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 Yeah I was rotating cam so lobe was facing away from the lifter do I compression test with a warm engine or cold I’m assuming warm as all materials would have expanded and give me a true reading? Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 Just to add the Rev counter when it reaches 4000 begins to bounce back and fourth between 3500 and 4500 rpm Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted September 11, 2019 Share Posted September 11, 2019 I'd definitely start with a compression test (warm ideally) but as long as the figures are above 140 ish and all within 15% of each other , they're within factory spec afaik for a early classic. If it was limp mode or a timing issue I'd have thought you'd have a code but if its modded and "chipped " instead of mapped ?. I don't know if it would store a code or whether it's just a sensor reading something out of the maps parameters (then cutting ignition) . If test comes back good ... Does it rev freely in neutral or at cruise (part throttle) . You've definitely plugged the coilpacks and injectors the right way round on both banks ? Fairly sure its light grey plugs to both side of each bank are for the rear cylinders for injectors and coilpacks . Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 It does throw an engine light like if you unplug the maf or the map so I know it stores codes because I used to get code 33 a lot Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 No it still stutters and pops in neutral and stand still but it will rev past it if you really push it but it sounds awful Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 Is there anyway I can send you a video of what it is doing Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted September 11, 2019 Share Posted September 11, 2019 I'm not sure how to post a vid on here other than YouTube, tbh I doubt it would help . If it wasn't doing it before the headgasket change ? Compression test ,to rule out valves being open and double check timing Marks. As unless you've plugged coilpacks or injectors in wrong those would probably be the first things to check after rebuilding the top end Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 11, 2019 Author Share Posted September 11, 2019 I was told the darker plugs are towards the gear box (coil packs and injectors) Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted September 11, 2019 Share Posted September 11, 2019 Tbh I've been running newage coilpacks for a long while and currently have a custom engine loom, so can't remember whether its dark at the front or back . Just know it's the same colour on each rear and on each front injector and coilpack Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 14, 2019 Author Share Posted September 14, 2019 This can’t be good surely all plugs are the same as this Quote Link to comment Share on other sites More sharing options...
Brucey 95wrx Posted September 14, 2019 Author Share Posted September 14, 2019 Quote Link to comment Share on other sites More sharing options...
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