joostvdw Posted February 26, 2009 Share Posted February 26, 2009 (edited) hi all, I've had this problem before but it has started to bother me. I have a stock EA82T with an open 2,5'' stainless exhaust from the turbo back. I've done headgaskets and every other seal and gasket on it last summer. So I know it's in good condition and I think that's strangely enough part of the problem... The problem is that it overboosts way to easily, it is set on 0,8 bar stock but it get over 1,2bar easily when I floor it in 3 and higer (lower gears are too short). Consequence is that it hits fuel cut and I bash my head against the steering wheel . After a couple of times the ECU learns that it's constantly running out of maps and starts to turn down all the maps, so the effect is that I don't have any power left . For instance, if I floor it in 4th on the highway, boost rises, it overboosts, ECU over compensates so boost (and power) drop again, pressure is safe again, ECU stops over compensating and boost starts to rise again, see where this is going? Power is coming and going in waves accompanied by the occasional fuel cut. And when it's not over compensating, it's still keeping the power low to prevent it from overboosting, which feels like I'm driving through corn-syrup. Summary: How to solve overboost? How to stop fuel cut? How to keep my foot of the gas Edited February 26, 2009 by joostvdw Link to comment Share on other sites More sharing options...
Turbone Posted February 26, 2009 Share Posted February 26, 2009 Do yoou have another ECU you could throw in there to check it? And Presslab had a electronic design to fool the MAF for the fuel cut. Link to comment Share on other sites More sharing options...
Txakura Posted February 26, 2009 Share Posted February 26, 2009 Skip? This sounds like something you might know. Link to comment Share on other sites More sharing options...
presslab Posted February 26, 2009 Share Posted February 26, 2009 Sounds like a wastegate problem. Try unplugging the WGDS. Here in the USDM the WGDS only works at high altitudes, you have more stock boost so perhaps it works all the time. Pressure test the wastegate system to ensure the actuator opens up and doesn't leak down. A MityVac or similar will work fine for this, or even a bicycle pump with a tire valve. Also, make sure all hoses are connected correctly. If that checks out ok try wiring the actuator open and see if it still overboosts. If it still does, then your wastegate is not flowing enough; either add exhaust restriction (cat), try porting the wastegate, or something more exotic like a new turbo or external wastegate. To reduce fuel cut the only correct way is to add more fuel with larger injectors and/or more fuel pressure. Only then should the MAF be adjusted. Link to comment Share on other sites More sharing options...
joostvdw Posted February 26, 2009 Author Share Posted February 26, 2009 thanks for the replies Sorry Rob, don't have a spare ECU (actually I do but it won't even start with that connected) so I can't swap it out. The EDM models don't have a WGDS, so the wastegate is directly plumbed into the pressure side of the turbo, this tiny hose is new, clean and correctly plumbed. I already swapped turbos once (so also a different wastegate) and both displayed these symptoms. I actually believe the engine just runs "too good" so the wastegate can't cope with all the exhaust gasses (this also explains why it's more noticeable when it's cold). Will fitting an intercooler solve this? Or just increase the flow of air? Are the wastegates easy to port? Can I modify the actuator rod so it opens further? Or maybe a seperate wastegate exhaust pipe (instead of the stock flange/blockoff plate). How about a external wastegate, any good? Man that's a lot of questions Link to comment Share on other sites More sharing options...
presslab Posted February 26, 2009 Share Posted February 26, 2009 thanks for the replies Sorry Rob, don't have a spare ECU (actually I do but it won't even start with that connected) so I can't swap it out. The EDM models don't have a WGDS, so the wastegate is directly plumbed into the pressure side of the turbo, this tiny hose is new, clean and correctly plumbed. I already swapped turbos once (so also a different wastegate) and both displayed these symptoms. I actually believe the engine just runs "too good" so the wastegate can't cope with all the exhaust gasses (this also explains why it's more noticeable when it's cold). Will fitting an intercooler solve this? Or just increase the flow of air? Are the wastegates easy to port? Can I modify the actuator rod so it opens further? Or maybe a seperate wastegate exhaust pipe (instead of the stock flange/blockoff plate). How about a external wastegate, any good? Man that's a lot of questions I'd bet adding a little backpressure would solve it then... I have two cats and 3" muffler with TD04L and have very stable boost, a little over 1 BAR. My car still has to pass California smog. Maybe adding one 2.5" cat would add just enough backpressure for you. Mother Earth would thank you, too. An intercooler will allow the engine to suck in more air and create more power, I don't think it will help your problem. You could try to make a "bellmouth" downpipe, I hear these work well for boost creep. When I last looked at the stock turbo, it looked like the wastegate door hit the downpipe flange, so a bellmouth would help here. Possibly just adding a bunch of gaskets would allow the door to open further. An external wastegate is a good idea but at that point you could just put on a TD04L turbo with a larger wastegate. Without a WGDS I am not sure what your ECU is doing to cut power. Link to comment Share on other sites More sharing options...
joostvdw Posted February 26, 2009 Author Share Posted February 26, 2009 I'd bet adding a little backpressure would solve it then... I have two cats and 3" muffler with TD04L and have very stable boost, a little over 1 BAR. My car still has to pass California smog. Maybe adding one 2.5" cat would add just enough backpressure for you. Mother Earth would thank you, too. An intercooler will allow the engine to suck in more air and create more power, I don't think it will help your problem. You could try to make a "bellmouth" downpipe, I hear these work well for boost creep. When I last looked at the stock turbo, it looked like the wastegate door hit the downpipe flange, so a bellmouth would help here. Possibly just adding a bunch of gaskets would allow the door to open further. An external wastegate is a good idea but at that point you could just put on a TD04L turbo with a larger wastegate. Without a WGDS I am not sure what your ECU is doing to cut power. I guess the ECU just leans the mixture to cut power? Sounds risky though... I think the biggest factor is cost, I really can't afford a cat or TD04 swap (since I'll need a lot more then just the turbo hardware) but I do have some spare time on my hands. Would a bellmouth solve my problems? edit: sorry, I just asked the same question again Thanks for the help, I will do some extra reading on the subject. Link to comment Share on other sites More sharing options...
4WDFrenzy Posted February 27, 2009 Share Posted February 27, 2009 IIRC, the MAF is what tells the ecu to cut boost. Basically, when the MAF voltage maxes out, the ecu runs out of maps to sustain the amount of airflow, causing everyone's favorite friend Fuel Cut, to rear it's ugly head. Patrick Link to comment Share on other sites More sharing options...
4WDFrenzy Posted February 27, 2009 Share Posted February 27, 2009 Oh yeah, and porting the wastegate is a piece of cake. If you can use a power drill, a screw driver, and a pair of needle nosed pliers, you can port the wastegate. All you need to do is get yourself some grinding stones, some tapping lube(WD-40 should work just fine), and remove the wastegate diaphram assembly. Then, fully extend the wastegate flapper open, give it a squirt of spray lube(don't over do it), take drill with said grinding stone attached(one that will fit inside the hole with a little room to spare) and go to town. Just beware not to make the hole larger than the wastegate flapper. Otherwise, you're asking for trouble and will need to acquire another exhaust housing and have to repeat the process all over(hopefully without repeating the overly enlarged hole!). After that, reattach turbo to manifold and away you go. Patrick Link to comment Share on other sites More sharing options...
joostvdw Posted March 1, 2009 Author Share Posted March 1, 2009 So I had a look today and the pivot point of the wastegate actuator was rusted solid After a good cleaning and greasing, it behaved again. Driveability has increased and boost stays longer on the 0,8 bars. It still overboosts but not as fast as it was doing the last couple of weeks. For now I'm pleased with it, the ECU will probably also stop bothering me as fuel cut will not be as frequent. When the weather clears (like in the summer) and I don't need it as often as I do now, I'll take it apart, make a bellmouth and port the wastegate. That should do the trick I'm still interested in modifying the MAF so I'll post a picture in the following days, perhaps Presslab can have a look at it? thanks for the help so far! Link to comment Share on other sites More sharing options...
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