Post Auto-X Twin turbo evaluation
03-29-22, 02:43 PM
#1
Post Auto-X Twin turbo evaluation
So, Rotorsports managed to find the major problem if you've been following my past threads. The cat ended up being clogged, resulting in an issue with my secondary transition. However, it would struggle to build boost, but still do it somewhat. I had the lines redone and I felt there was an exhaust leak, so I had the two cat gaskets replaced as well. After this, the car had no secondary boost whatsoever.
My theory on this is, the cat was clogged from the beginning, but the 26 year old gaskets allowed it to bleed off some of the obstruction in the cat and produce some boost. Rotorsports ended up changing out the cat for a resonated midpipe, and the problem went away, for the most part (they said it was a perfect 10-8-10.)
I managed to get the car back the day they said it was ready, and took it to autocross alittle over a week ago. I noticed on the way there/during the autocross, that I still have a problem present. I can go WOT in first, and the primary will build strong boost, the changeover occurs at 4500, I get a drop off of boost and there will be a momentary lull of maybe a second and a half, and then it will spring to life back to 10-11 psi, and hold that to redline.
The second issue - If I let off the throttle completely in first gear after going WOT/building primary boost and get back on it, the turbo will now struggle to build boost (this is before the 4500 changeover.) This also happens after the changeover as well I believe.
So at this point I'm unsure of what it can be. I've heard people say check valves, but I'm running DaleClark Viton's, and he's mentioned that out of the countless ones he's sold, a handful have been bad, which is a very low failure rate, so one being bad I'd say is possible, though not probable.
I am running the PFC, with who knows what map on it (came that way from Japan), but I doubt they would have the turbo system set up to behave oddly like that. I thought about doing the initialization on the commander, but I'm not sure if that would help or potentially cause more issues.
Could I have potentially bought a non working component when I re did the whole system at this point? Possibly, but Tomsn16 vetts his parts very well, so I don't think that would be the case either.
At this point I am scratching my head. The car did okay at autocross, but when I accel off and there's a 1.5~ second period where it's struggling to build boost back up, that's noticeably going to effect my times.
Any thoughts?
My theory on this is, the cat was clogged from the beginning, but the 26 year old gaskets allowed it to bleed off some of the obstruction in the cat and produce some boost. Rotorsports ended up changing out the cat for a resonated midpipe, and the problem went away, for the most part (they said it was a perfect 10-8-10.)
I managed to get the car back the day they said it was ready, and took it to autocross alittle over a week ago. I noticed on the way there/during the autocross, that I still have a problem present. I can go WOT in first, and the primary will build strong boost, the changeover occurs at 4500, I get a drop off of boost and there will be a momentary lull of maybe a second and a half, and then it will spring to life back to 10-11 psi, and hold that to redline.
The second issue - If I let off the throttle completely in first gear after going WOT/building primary boost and get back on it, the turbo will now struggle to build boost (this is before the 4500 changeover.) This also happens after the changeover as well I believe.
So at this point I'm unsure of what it can be. I've heard people say check valves, but I'm running DaleClark Viton's, and he's mentioned that out of the countless ones he's sold, a handful have been bad, which is a very low failure rate, so one being bad I'd say is possible, though not probable.
I am running the PFC, with who knows what map on it (came that way from Japan), but I doubt they would have the turbo system set up to behave oddly like that. I thought about doing the initialization on the commander, but I'm not sure if that would help or potentially cause more issues.
Could I have potentially bought a non working component when I re did the whole system at this point? Possibly, but Tomsn16 vetts his parts very well, so I don't think that would be the case either.
At this point I am scratching my head. The car did okay at autocross, but when I accel off and there's a 1.5~ second period where it's struggling to build boost back up, that's noticeably going to effect my times.
Any thoughts?
Last edited by SwappedNA; 03-29-22 at 03:41 PM. Reason: Grammar.
03-29-22, 03:30 PM
#2
RX-7 Bad Ass
iTrader: (55)
You are getting there!
That makes sense with the cat. With the exhaust leaks you were getting more flow than through the plugged cat so once that was fixed you dropped boost.
The stock FD cat is VERY hardy and it's extremely uncommon to hear of one that's dead/clogged.
I think the transition issue is probably with the turbo control door. If you look at the vacuum diagram -
https://www.rx7club.com/3rd-generati...-turbo-749702/
Up in the top left you see one labelled "solenoid valve (turbo control)" - this is a common culprit to go out. Mine is the only one of my solenoids I had problems with. I could make good boost and transition but then it would stick and keep the door open when going back to low RPM.
Teeing your boost gauge into the vacuum lines for the turbo control would be a fast way to pin the problem down.
Or come to Deal's Gap at the end of April and I'll take a look at it for you
Dale
That makes sense with the cat. With the exhaust leaks you were getting more flow than through the plugged cat so once that was fixed you dropped boost.
The stock FD cat is VERY hardy and it's extremely uncommon to hear of one that's dead/clogged.
I think the transition issue is probably with the turbo control door. If you look at the vacuum diagram -
https://www.rx7club.com/3rd-generati...-turbo-749702/
Up in the top left you see one labelled "solenoid valve (turbo control)" - this is a common culprit to go out. Mine is the only one of my solenoids I had problems with. I could make good boost and transition but then it would stick and keep the door open when going back to low RPM.
Teeing your boost gauge into the vacuum lines for the turbo control would be a fast way to pin the problem down.
Or come to Deal's Gap at the end of April and I'll take a look at it for you
Dale
03-29-22, 03:38 PM
#3
You are getting there!
That makes sense with the cat. With the exhaust leaks you were getting more flow than through the plugged cat so once that was fixed you dropped boost.
The stock FD cat is VERY hardy and it's extremely uncommon to hear of one that's dead/clogged.
I think the transition issue is probably with the turbo control door. If you look at the vacuum diagram -
https://www.rx7club.com/3rd-generati...-turbo-749702/
Up in the top left you see one labelled "solenoid valve (turbo control)" - this is a common culprit to go out. Mine is the only one of my solenoids I had problems with. I could make good boost and transition but then it would stick and keep the door open when going back to low RPM.
Teeing your boost gauge into the vacuum lines for the turbo control would be a fast way to pin the problem down.
Or come to Deal's Gap at the end of April and I'll take a look at it for you
Dale
That makes sense with the cat. With the exhaust leaks you were getting more flow than through the plugged cat so once that was fixed you dropped boost.
The stock FD cat is VERY hardy and it's extremely uncommon to hear of one that's dead/clogged.
I think the transition issue is probably with the turbo control door. If you look at the vacuum diagram -
https://www.rx7club.com/3rd-generati...-turbo-749702/
Up in the top left you see one labelled "solenoid valve (turbo control)" - this is a common culprit to go out. Mine is the only one of my solenoids I had problems with. I could make good boost and transition but then it would stick and keep the door open when going back to low RPM.
Teeing your boost gauge into the vacuum lines for the turbo control would be a fast way to pin the problem down.
Or come to Deal's Gap at the end of April and I'll take a look at it for you
Dale
I do have a spare mechanical boost gauge laying around (who knew harbor freight made those). I'm guessing the UIM has to come off to access that?
Last edited by SwappedNA; 03-29-22 at 03:41 PM.
03-30-22, 08:22 AM
#4
RX-7 Bad Ass
iTrader: (55)
There are multiple places you can tee in. The turbo control door has a vacuum side and a pressure side. If you tee into the pressure side, it should be atmospheric pressure at low RPM and boost pressure at high RPM, dropping back to atmospheric when RPM's drop. Vacuum side is the same thing, except it's vacuum or atmospheric.
Just look at the turbo control diagram. If one side or the other isn't working like it should then you can start troubleshooting from there.
Dale
Just look at the turbo control diagram. If one side or the other isn't working like it should then you can start troubleshooting from there.
Dale
03-30-22, 11:45 AM
#5
Try this: https://www.rx7club.com/3rd-generati...ctive-1120259/
Been meaning to do this myself since I'm having the same problem.
Been meaning to do this myself since I'm having the same problem.
03-30-22, 12:40 PM
#6
RX-7 Bad Ass
iTrader: (55)
Try this: https://www.rx7club.com/3rd-generati...ctive-1120259/
Been meaning to do this myself since I'm having the same problem.
Been meaning to do this myself since I'm having the same problem.
You need to tee your boost gauge in and determine it's the problem before just doing it.
Dale
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