Bugeye WRX Misfire/Judder
14 February 2024, 09:39 AM
#1
Scooby Newbie
Thread Starter
Bugeye WRX Misfire/Judder
Hi People,
Car is fairly standard 2002 WRX Bugeye, has a full decat, K&N Panel Filter, Classic 3 port boost solenoid & Walbro with aftermarket FPR & STi Intercooler. Currently on 78K Miles.
I brought the car cheap with known issues (you can never have enough projects) this is the last one to solve and proving problematic. It would appear a few people have had a go a the parts cannon approach and failed, with a few bodges corrected.
Car starts runs and idle’s perfect. When driving as soon as you attempt more than 1/4 throttle and the car starts coming into boost, it starts stuttering/missing and jerking fairly violently, rpm and load is never consistent and sometimes pulls clean all the way through and feels like no problems, but this is rare. CEL Flashes for gross misfire but no codes. are
I have checked/logged/been through the following, faults have been found with pretty much everything, not in any particular order just as i think about what i’ve done in short;
Car uses no oil or coolant.
Compression tested at 150 psi with 5 psi between all, one of the most even i’ve ever seen after 100’s of compression tests.
New coils & Plugs correctly gapped.
Timing belt/water pump replaced.
New MAF
New front O2
New PCV Valve
New fuel filter
Plugs all the same with no oil or wetness on any.
Car is mapped to 18 psi, target fuel tables look normal (im no mapper but fairly familiar with what the values should be/ looked at lots of other maps from the Romraider forum). Also compared to Standard map.
I’ve done some standalone ignition maps but not much on the oem/opensource/remap stuff so maybe im missing something in the map but assume any major faults would cause consistent issues.
Injector’s cleaned and checked, all injector values are for the standard injectors in the map. Fuel pump (Walbro 255) and after market FPR new, set to 3 bar with vacuum line removed at idle. Fuel pump controller swapped with a known good one.
Had many many boost/vac leaks, all these rectified and new HKS Dump Valve fitted as the forge that came with the car was also leaking. Hits target boost of 18 psi and holds steady even with the rough running, not hitting fuel cut due to overboost as the limit has been raised to suit. (Checked with logs) also pressure tested holds pressure fine now.
Assuming the car has been mapped with the 3 port with no restrictor as this setup is the only way to get full boost. Valve tested off the car and fine.
Exhaust had a few blows in mid section when replacing gaskets i examined the turbo which had to much play in my opinion as it could touch housing, also had a couple of thou play in and out as well. Wasnt happy with this even though it made full boost with no suspicious noises so swapped with a known good identical turbo.
Fitted a AEM Wideband, this showed extreme rich running, curing the boost leaks only slightly helped this, checked the fuel trims and the ecu was pulling fuel in closed loop, -14.99 maxed out at idle, - 10% varying in other ranges, checked the MAF Scale as assumed this would be standard/slightly tweaked with the standard airbox/MAF in place, however it was 13% going upto 18% higher at top end higher than standard, suspect someone has tried to map round a leak they couldn’t find. Re flashed with standard MAF Scale and fuel trims returned within + - 3%, apart from range D which i assume i didnt enter with minimal driving, this stayed at 0. This cured the running rich but not the judder/misfire. AFR stays bang on with target upto the misfire event then jumps about as you’d with a gross miss. On the odd clean pull i do get AFR Stays as expected. ( Logged via romraider)
Car is detecting no Knock in either learning tables or on logs via FLKC and other knock channels.
Probably some other obvious things i’ve forgotten i’ve changed without even thinking about it.
Any advice/ideas welcome!
Possible electrical/wiring fault?
Apologies for the long post!
Cheers in advance for any help!
Car is fairly standard 2002 WRX Bugeye, has a full decat, K&N Panel Filter, Classic 3 port boost solenoid & Walbro with aftermarket FPR & STi Intercooler. Currently on 78K Miles.
I brought the car cheap with known issues (you can never have enough projects) this is the last one to solve and proving problematic. It would appear a few people have had a go a the parts cannon approach and failed, with a few bodges corrected.
Car starts runs and idle’s perfect. When driving as soon as you attempt more than 1/4 throttle and the car starts coming into boost, it starts stuttering/missing and jerking fairly violently, rpm and load is never consistent and sometimes pulls clean all the way through and feels like no problems, but this is rare. CEL Flashes for gross misfire but no codes. are
I have checked/logged/been through the following, faults have been found with pretty much everything, not in any particular order just as i think about what i’ve done in short;
Car uses no oil or coolant.
Compression tested at 150 psi with 5 psi between all, one of the most even i’ve ever seen after 100’s of compression tests.
New coils & Plugs correctly gapped.
Timing belt/water pump replaced.
New MAF
New front O2
New PCV Valve
New fuel filter
Plugs all the same with no oil or wetness on any.
Car is mapped to 18 psi, target fuel tables look normal (im no mapper but fairly familiar with what the values should be/ looked at lots of other maps from the Romraider forum). Also compared to Standard map.
I’ve done some standalone ignition maps but not much on the oem/opensource/remap stuff so maybe im missing something in the map but assume any major faults would cause consistent issues.
Injector’s cleaned and checked, all injector values are for the standard injectors in the map. Fuel pump (Walbro 255) and after market FPR new, set to 3 bar with vacuum line removed at idle. Fuel pump controller swapped with a known good one.
Had many many boost/vac leaks, all these rectified and new HKS Dump Valve fitted as the forge that came with the car was also leaking. Hits target boost of 18 psi and holds steady even with the rough running, not hitting fuel cut due to overboost as the limit has been raised to suit. (Checked with logs) also pressure tested holds pressure fine now.
Assuming the car has been mapped with the 3 port with no restrictor as this setup is the only way to get full boost. Valve tested off the car and fine.
Exhaust had a few blows in mid section when replacing gaskets i examined the turbo which had to much play in my opinion as it could touch housing, also had a couple of thou play in and out as well. Wasnt happy with this even though it made full boost with no suspicious noises so swapped with a known good identical turbo.
Fitted a AEM Wideband, this showed extreme rich running, curing the boost leaks only slightly helped this, checked the fuel trims and the ecu was pulling fuel in closed loop, -14.99 maxed out at idle, - 10% varying in other ranges, checked the MAF Scale as assumed this would be standard/slightly tweaked with the standard airbox/MAF in place, however it was 13% going upto 18% higher at top end higher than standard, suspect someone has tried to map round a leak they couldn’t find. Re flashed with standard MAF Scale and fuel trims returned within + - 3%, apart from range D which i assume i didnt enter with minimal driving, this stayed at 0. This cured the running rich but not the judder/misfire. AFR stays bang on with target upto the misfire event then jumps about as you’d with a gross miss. On the odd clean pull i do get AFR Stays as expected. ( Logged via romraider)
Car is detecting no Knock in either learning tables or on logs via FLKC and other knock channels.
Probably some other obvious things i’ve forgotten i’ve changed without even thinking about it.
Any advice/ideas welcome!
Possible electrical/wiring fault?
Apologies for the long post!
Cheers in advance for any help!
14 February 2024, 07:41 PM
#4
Scooby Newbie
Thread Starter
Update if anyone's interested/to give a possible solution for similar symptoms when you've checked everything else;
One broken wire on the brown harness plug just behind the battery, not noticeable unless you take all the clips off/undo the connectors. Wire was making contact from the bend in the harness only. Fixed the wire and car now runs like a dream and pulls strong.
Past couple of months of headaches all forgotten about the second it comes on boost!
One broken wire on the brown harness plug just behind the battery, not noticeable unless you take all the clips off/undo the connectors. Wire was making contact from the bend in the harness only. Fixed the wire and car now runs like a dream and pulls strong.
Past couple of months of headaches all forgotten about the second it comes on boost!
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