Brian_C1 Posted July 29, 2020 Share Posted July 29, 2020 Anyone any ideas on why my second turbo sometimes doesn't engage? Particularly in 1st gear but in all gears if I build revs slowly and floor it at 5k there's no boost, if I floor it early before second turbo is due to come in it usually boosts fine and if it doesn't coming off the power and going back on usually engages it fine. I've replaced all vacuum lines that are easily visible on top of the engine, I've replaced the turbo join pipes that are prone to collapsing what else could causes this? VSV failure? Thanks in advance Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted July 29, 2020 Share Posted July 29, 2020 I would say IACV VSV. Had a few with similar symptoms that are intermittent. Quote Link to comment Share on other sites More sharing options...
Rob W Posted July 29, 2020 Share Posted July 29, 2020 I did have this issue a year or so ago, whilst carrying out a load of work within the engine bay I changed all vacuum hoses and vsv’s but after doing that I still had the same issue. I manually pulled the EGCV actuator rod back and fourth giving it a clean also, the car has never done it since. Worth a shot, will only take you 5 minutes. Quote Link to comment Share on other sites More sharing options...
Brian_C1 Posted July 29, 2020 Author Share Posted July 29, 2020 I would say IACV VSV. Had a few with similar symptoms that are intermittent. I did have this issue a year or so ago, whilst carrying out a load of work within the engine bay I changed all vacuum hoses and vsv’s but after doing that I still had the same issue. I manually pulled the EGCV actuator rod back and fourth giving it a clean also, the car has never done it since. Worth a shot, will only take you 5 minutes. Cheers for the replies guys, I've ordered a new IACV anyway just now for €50 delivered ex customs if it gets stopped but I'll clean the EGCV actuator as well now this evening or in the morning, no harm in doing both! Quote Link to comment Share on other sites More sharing options...
Boyne Posted July 29, 2020 Share Posted July 29, 2020 Anyone any ideas on why my second turbo sometimes doesn't engage? Particularly in 1st gear but in all gears if I build revs slowly and floor it at 5k there's no boost, if I floor it early before second turbo is due to come in it usually boosts fine and if it doesn't coming off the power and going back on usually engages it fine. I've replaced all vacuum lines that are easily visible on top of the engine, I've replaced the turbo join pipes that are prone to collapsing what else could causes this? VSV failure? Thanks in advance Had similar issue when removed egr turned out forgot to hook pipe back into the pressure tank, very hard get access to, but what your describing is exactly what mine was doing. Quote Link to comment Share on other sites More sharing options...
Scooter Posted July 30, 2020 Share Posted July 30, 2020 I manually pulled the EGCV actuator rod back and fourth giving it a clean also, the car has never done it since. Worth a shot, will only take you 5 minutes. QUOTE FROM THE GREAT IAN C Sounds like the EGCV not opening. As turbo 2 hasn't got anything spinning it up, turbo 1's boost takes the path of least resistance which is straight through turbo 2, backwards, and out to the air filter. Where it gets sucked back into #1 again. Car ends up feeling a tad underpowered You can trap a bit of tinfoil between the EGCV actuator cam and it's screwstop, and go for a hoon. If the tinfoil has gone, it's opening at least partially. If it's still there and you went over 4000rpm, it's not opening... -Ian Do as Rob said, there is a chance the inside is coked up a bit and the flap is snagging and taking more effort (than the air pressure can't quite overcome) Moving it by hand through its range of motion might free it all back up? Also there is a nut on a tread that's a stop so you could wind that a touch to move the internal flap off (or barely touching) the housing to again remove the chance of stiction. Quote Link to comment Share on other sites More sharing options...
Brian_C1 Posted July 31, 2020 Author Share Posted July 31, 2020 Had similar issue when removed egr turned out forgot to hook pipe back into the pressure tank, very hard get access to, but what your describing is exactly what mine was doing. Cheers Nigel, I'll take a look at that as well later today QUOTE FROM THE GREAT IAN C Sounds like the EGCV not opening. As turbo 2 hasn't got anything spinning it up, turbo 1's boost takes the path of least resistance which is straight through turbo 2, backwards, and out to the air filter. Where it gets sucked back into #1 again. Car ends up feeling a tad underpowered You can trap a bit of tinfoil between the EGCV actuator cam and it's screwstop, and go for a hoon. If the tinfoil has gone, it's opening at least partially. If it's still there and you went over 4000rpm, it's not opening... -Ian Do as Rob said, there is a chance the inside is coked up a bit and the flap is snagging and taking more effort (than the air pressure can't quite overcome) Moving it by hand through its range of motion might free it all back up? Also there is a nut on a tread that's a stop so you could wind that a touch to move the internal flap off (or barely touching) the housing to again remove the chance of stiction. Cheers scooter didn't get a chance to look at it yet but hopefully today I'll get a hour to go through all the suggestions here, cheers Quote Link to comment Share on other sites More sharing options...
Scooter Posted July 31, 2020 Share Posted July 31, 2020 Good info and other links within this that should help.... https://www.mkivsupra.net/vbb/showthread.php?354424-Resolved-Lost-boost-and-no-second-turbo&highlight=exhaust Quote Link to comment Share on other sites More sharing options...
jaymdee Posted August 2, 2020 Share Posted August 2, 2020 HaHa, was about to post a link to my thread from last year and then clicked on Scooters link, thinking it would be the Ian C turbo thread and it was mine. Yes. Replacing the two small vacuum hoses down the back of the engine which run to/from the pressure tank totally cured the problem. Took me about 30 hours to remove, clean, test all VSVs etc and refit, but definitely worth it. (I’m very slow, lol!!) Quote Link to comment Share on other sites More sharing options...
Brian_C1 Posted August 2, 2020 Author Share Posted August 2, 2020 HaHa, was about to post a link to my thread from last year and then clicked on Scooters link, thinking it would be the Ian C turbo thread and it was mine. Yes. Replacing the two small vacuum hoses down the back of the engine which run to/from the pressure tank totally cured the problem. Took me about 30 hours to remove, clean, test all VSVs etc and refit, but definitely worth it. (I’m very slow, lol!!) I've read about those before but always put it off and to be honest didn't even check the accessibility, how difficult is it to change those? How much disassembly needs to be done to get to them Quote Link to comment Share on other sites More sharing options...
jaymdee Posted August 3, 2020 Share Posted August 3, 2020 I've read about those before but always put it off and to be honest didn't even check the accessibility, how difficult is it to change those? How much disassembly needs to be done to get to them I ‘think’ it can be done by someone with very small hands without removing anything, but I removed all intake pipes, the small bore black metal turbo pipe work, VSVs and actuators the IACV, turbo heat shield and loosened T1 (front turbo) to get some pipes off. Basically everything except the turbos. And it was still difficult. I used a bic biro to stretch new silicon hoses over and then dropped onto the 2 little hard pipes poking up and then squeezed the biro out. As I said, I reckon it took me about 30 hours going slow and methodically, plus I electrically tested all the VSVs. To be honest was very surprised I managed it and it worked. I did find a few small holes in the 2 hoses which connect to/from the pressure tank. Quote Link to comment Share on other sites More sharing options...
Brian_C1 Posted August 4, 2020 Author Share Posted August 4, 2020 I ‘think’ it can be done by someone with very small hands without removing anything, but I removed all intake pipes, the small bore black metal turbo pipe work, VSVs and actuators the IACV, turbo heat shield and loosened T1 (front turbo) to get some pipes off. Basically everything except the turbos. And it was still difficult. I used a bic biro to stretch new silicon hoses over and then dropped onto the 2 little hard pipes poking up and then squeezed the biro out. As I said, I reckon it took me about 30 hours going slow and methodically, plus I electrically tested all the VSVs. To be honest was very surprised I managed it and it worked. I did find a few small holes in the 2 hoses which connect to/from the pressure tank. Perfect cheers, I'll take a look and see can I get access without taking too much apart! Either way I'll have to set aside a day someday to do it as at this stage I'm fairly sure the issue is with the pipes back there. Quote Link to comment Share on other sites More sharing options...
mike33 Posted August 4, 2020 Share Posted August 4, 2020 My 2nd turbo stopped spoiling up check all hoses and vvc were all OK! I took it to SRD and found after alot of tests my fuel pump was rusty and when the 2nd turbo was going to cut in, the car was going lean and was running out of fuel in the system! Just another thing to possible check! Quote Link to comment Share on other sites More sharing options...
Brian_C1 Posted August 5, 2020 Author Share Posted August 5, 2020 My replacement IACV VSV arrived yesterday and I replaced it, looks to have solved 99% of the issues, first turbo boosting better, second turbo boosting all the time now whether full or half throttle. Only possibly issue is in first gear second turbo might be bit slow on boost ≈5.5k rpm vs 4.5k in every other gear, is this normal or is likely there's a small boost leak somewhere probably the hoses going to the pressure tank Quote Link to comment Share on other sites More sharing options...
fastphil666 Posted August 10, 2020 Share Posted August 10, 2020 Mine seems similar, if i stick my foot down it gets to 4k and takes off. However if im in manual mode, drop it to second around 40mph, then hoof it, it doesnt always hit full boost. I havent changed the pipes to the presure tank, but have replaced all the others and tested all vsv's. All ok. My egbv actuator looks a touch rusty, freed it up a bit the otger morning before driving. Should you be able to move the actuator rod by hand? Quote Link to comment Share on other sites More sharing options...
Scooter Posted August 10, 2020 Share Posted August 10, 2020 It harder than I imagined, but yes I think I did it by hand.....reach to the rotating bit not the rod itself (again from memory) Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted August 10, 2020 Share Posted August 10, 2020 My replacement IACV VSV arrived yesterday and I replaced it, looks to have solved 99% of the issues, first turbo boosting better, second turbo boosting all the time now whether full or half throttle. Only possibly issue is in first gear second turbo might be bit slow on boost ≈5.5k rpm vs 4.5k in every other gear, is this normal or is likely there's a small boost leak somewhere probably the hoses going to the pressure tank The load on the engine in first gear is less than the other gears, so its not unusual for the boost to come on a bit later. Even if the valves are working as intended, the gear itself is over fairly quick and the time for boost to be produced is less so it happens later relative to higher gears. Edit: I find this even more noticeable on UK spec turbo's as the steel wheels take a bit longer to spool anyway. Quote Link to comment Share on other sites More sharing options...
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