Supra Turbo S-AFC bad issues!!
09-25-2003, 05:15 PM
#1
Ghost
Thread Starter
Supra Turbo S-AFC bad issues!!
Ok, I worked on the Accord for two years and never got it finished before giving up.
I've owned the Supra for one stinkin week and already it doesn't run.
Here's the deal. WHen I picked the car up from Memphis, TN two weekends ago, the guy hadn't really played with it in months. Ok at all, since he did the single conversion. He went ahead and re-initialized the S-AFC and through a Supra tuner in Atlanta, found out that it naturally runs pretty rich when default, at least on the MKIV. Since he had no idea what the massive difference in air volume that the single has over the stock twins, he thought this was a pretty decent baseline and would certainly get the car back to VA Beach.
And it surely did, although the fact that it was running rich was apparent as hell. Smoke, rough idle, stalling when I let the engine drop from 2,500 RPMs or more. Nothing that concerned me, I just made the note to get it tuned immediately, or I would worry about the fouled plugs and clogged sensors.
Well, Isabele came and the Navy went. Lucky for me, VR-4ever was going nowhere and could watch the Supra for me. Thigns got a bit mixed up here.
Through an interesting line of thinking, he took the car to NOPI Nat's in Atlanta while I was at sea. Granted, it was safe from Isabele, but had I known about the trip I would have warned him that the turbo is surging (no BOV) and the fuel map was just plain fucked. Be it as it may, he made it there no problems, but on the way back shit started coming apart.
Apparently, he shifted from 5th to 6th and went to reapply throttle, and the AFC started cutting the throttle back more and more until it was practically stalling out. He pulled over and let it sit for about 15 minutes and when he came back it was running again, but extremely rough. I don't know how long he ran it for after that.
When I got back, he had already left for another business trip and I only had broken phone conversations with ihm, so this is pretty much all I know about the initial problem. What I do know is that when I got in it, it wouldn't run at all. I could smell hella fuel and nothing else seemed wrong, so I bought 6 new plugs and put them in. I finally got it to start, though I had to give it throttle to start and keep it running.
At this point I'm losing my mind. I thought the damn engine was blown or something, I just didn't know. So I went and found some basic set-ups for the MKIV Supra and re-initialized the S-AFC and set it up again to default. 6 cylinders, upwards throttle, blah blah. I succeded in getting it to idle now.
This is where it gets weird, and where it currently stands. I took it on a test drive to make sur eit was good, because it was idling like a champ right then. As soon as the turbo started to spool, I heard what sounded like air escaping, then WHAM, the engine just dumped a massive amount of fuel and flooded the engine out to a stall. Somehow the plugs didn't foul out and I got it running again, at least on minimal cylinders, then eventually it settled out and ran fine again. I can still get it to idle and drive just fine until I hit exactly ZERO bar, then it dumps, floods and tries to stall, unless I keep it in gear and feather the throttle while it figures out how to settle itself again.
I checked all my I/C piping, everything is good. I obviously couldn't leak test, but I don't see that causing the engine to go so rich like that. I don't get check engine anymore, even when it floods, and it smokes like a chimney like it's just always running rich.
Something else strange that HAS to be the biggest symptom, though I don't have a clue what to do about it. When I drove it back from MEmphis, I could either watch the 2.0 boost gauge in dash, or watch the digital read-out form the S-AFC. THey were not exactly on each other but pretty damn close. NOW, the S-AFC doesn't go above -700 mmHG, despite the in-dash telling me it's building to the dramatic 0 bar, of course no more due to the problem. When I called the old owner, he told me I was crazy thinking I could measure boost from the S-AFC, despite my swearing that I was getting hella jollies watching the thing edge past 1 bar on the highway. Regardless, it doesn't now, so how did it before?! There's no sensor anywhere on the intake tract, so where the hell did it get the info on manifold presure?!
Wow, I gotta be setting a record for longest post, but I Wanted all the info laid out. Now, who thinks they can help me out on this one! It's a doozy, I know. Tomorrow Iwant to get it to Auto Solutions and have the tuning gurus ther take a look and see what they think, so if you think you may know and want to give a hand, and happen to be aroun dLynnhaven, PLEASE come on by! Thanks for reading this far.
-Merrill.
I've owned the Supra for one stinkin week and already it doesn't run.
Here's the deal. WHen I picked the car up from Memphis, TN two weekends ago, the guy hadn't really played with it in months. Ok at all, since he did the single conversion. He went ahead and re-initialized the S-AFC and through a Supra tuner in Atlanta, found out that it naturally runs pretty rich when default, at least on the MKIV. Since he had no idea what the massive difference in air volume that the single has over the stock twins, he thought this was a pretty decent baseline and would certainly get the car back to VA Beach.
And it surely did, although the fact that it was running rich was apparent as hell. Smoke, rough idle, stalling when I let the engine drop from 2,500 RPMs or more. Nothing that concerned me, I just made the note to get it tuned immediately, or I would worry about the fouled plugs and clogged sensors.
Well, Isabele came and the Navy went. Lucky for me, VR-4ever was going nowhere and could watch the Supra for me. Thigns got a bit mixed up here.
Through an interesting line of thinking, he took the car to NOPI Nat's in Atlanta while I was at sea. Granted, it was safe from Isabele, but had I known about the trip I would have warned him that the turbo is surging (no BOV) and the fuel map was just plain fucked. Be it as it may, he made it there no problems, but on the way back shit started coming apart.
Apparently, he shifted from 5th to 6th and went to reapply throttle, and the AFC started cutting the throttle back more and more until it was practically stalling out. He pulled over and let it sit for about 15 minutes and when he came back it was running again, but extremely rough. I don't know how long he ran it for after that.
When I got back, he had already left for another business trip and I only had broken phone conversations with ihm, so this is pretty much all I know about the initial problem. What I do know is that when I got in it, it wouldn't run at all. I could smell hella fuel and nothing else seemed wrong, so I bought 6 new plugs and put them in. I finally got it to start, though I had to give it throttle to start and keep it running.
At this point I'm losing my mind. I thought the damn engine was blown or something, I just didn't know. So I went and found some basic set-ups for the MKIV Supra and re-initialized the S-AFC and set it up again to default. 6 cylinders, upwards throttle, blah blah. I succeded in getting it to idle now.
This is where it gets weird, and where it currently stands. I took it on a test drive to make sur eit was good, because it was idling like a champ right then. As soon as the turbo started to spool, I heard what sounded like air escaping, then WHAM, the engine just dumped a massive amount of fuel and flooded the engine out to a stall. Somehow the plugs didn't foul out and I got it running again, at least on minimal cylinders, then eventually it settled out and ran fine again. I can still get it to idle and drive just fine until I hit exactly ZERO bar, then it dumps, floods and tries to stall, unless I keep it in gear and feather the throttle while it figures out how to settle itself again.
I checked all my I/C piping, everything is good. I obviously couldn't leak test, but I don't see that causing the engine to go so rich like that. I don't get check engine anymore, even when it floods, and it smokes like a chimney like it's just always running rich.
Something else strange that HAS to be the biggest symptom, though I don't have a clue what to do about it. When I drove it back from MEmphis, I could either watch the 2.0 boost gauge in dash, or watch the digital read-out form the S-AFC. THey were not exactly on each other but pretty damn close. NOW, the S-AFC doesn't go above -700 mmHG, despite the in-dash telling me it's building to the dramatic 0 bar, of course no more due to the problem. When I called the old owner, he told me I was crazy thinking I could measure boost from the S-AFC, despite my swearing that I was getting hella jollies watching the thing edge past 1 bar on the highway. Regardless, it doesn't now, so how did it before?! There's no sensor anywhere on the intake tract, so where the hell did it get the info on manifold presure?!
Wow, I gotta be setting a record for longest post, but I Wanted all the info laid out. Now, who thinks they can help me out on this one! It's a doozy, I know. Tomorrow Iwant to get it to Auto Solutions and have the tuning gurus ther take a look and see what they think, so if you think you may know and want to give a hand, and happen to be aroun dLynnhaven, PLEASE come on by! Thanks for reading this far.
-Merrill.
09-25-2003, 05:34 PM
#3
Ghost
Thread Starter
No, I'm not at all sure it's set up...I went off the MKIV website for setting it up though, so unless the guy who installed it did some funky stuff wiht it, it should have been right. I set it up for hot-wire, ch. 12-12, and 1-1. What the hell that means, I have no idea...I'm so dumb with this AFC thing, it's not even cool. Anyway, the mods are in my sig, but I'll say them again...PT-57 turbo running about 1 bar (15 psi), Innovative Tech. wastegate, the S-AFC, 3 inch downpipe and catback exhaust is pretty much all I know about for the mods when I bought it. I do know that the o2 is narrowband, he almost installed a wideband but decided to sell it instead. So there it is...
09-25-2003, 06:03 PM
#4
~
Join Date: Nov 2002
Location: FL / VA
Posts: 6,885
Likes: 0
Received 0 Likes
on
0 Posts
o2 sensor problem? maf? plug wires ok? coil(s)? maybe you could ask someone local with a single turbo supra if you could borrow their ecu? cats clogged? i really no nothing about supras im just kinda listin things that i think sound like they might be related to problems like yours. good luck bro, that car is way too pretty to be sitting dead in a driveway 
09-25-2003, 06:16 PM
#5
Ghost
Thread Starter
o2, I would think it wouldn't run at all, but it runs fine (now) until positive pressure in the intake manifold.
MAF, possibility for sure.
ignition system is fine, I checked it all out when I replaced the plugs.
I don't knwo about swapping ECUs...yikes. Thanks for the though on the MAF though, I'll have to lok into that...but how the hell do I test it out!?
MAF, possibility for sure.
ignition system is fine, I checked it all out when I replaced the plugs.
I don't knwo about swapping ECUs...yikes. Thanks for the though on the MAF though, I'll have to lok into that...but how the hell do I test it out!?
09-25-2003, 06:34 PM
#6
~
Join Date: Nov 2002
Location: FL / VA
Posts: 6,885
Likes: 0
Received 0 Likes
on
0 Posts
there are ways to test voltage to the MAF. however unless your MAF is just completely screwed i doubt it would cause your car to be that bad. take it out, inspect that nothing has damaged the sensors (look like little filament wires), spray some brake cleaner on them to clean them off. i would think that a single turbo conversion would require some serious tuning work considering the change of amount of air being forced into the motor. tried posting this on a supra forum? also the o2 sensor probably wouldnt cause the car to not run at all, but it would cause it to stumble. have you double checked there are no significant vacuum leaks?
09-25-2003, 06:36 PM
#7
Ghost
Thread Starter
One small Northeast Supra forum. THe main one is down, or at least I can't get to it from work...I dunno. Vaccuum leaks I'm pretty sure I"m good...it's a boost leak I'm worried about, I'm think maybe one sensor feels the air from the turbo, but one later doesn't or something...I dunno...blah. Lots of random thoughts, but nothing that seemed solid in my head, except for the obvious lack of tuning knowledge I have, lol.
09-25-2003, 07:42 PM
#8
Registered Member
Join Date: Nov 2002
Posts: 1,144
Likes: 0
Received 0 Likes
on
0 Posts
I have my stock coil packs in the garage if you would like to swap and see if thats a problem. Also, I have the stock MAF sensor and MAP sensor too. Time to go over the car inch by inch and make sure also that the S-AFC is connected correctly.
09-25-2003, 07:47 PM
#9
Ghost
Thread Starter
^
|
|
VERY interested in MAF/MAP...I think that could be it if tuning doesn't do it. Inch-by-inch, to check the wires, too...I sorta did for hoses and vacuum lines...but maybe not as close as I should have.
PS- I DID find a hose that was dangling, it wa sconnected to something directly below the battery...any idea what that would have been? THe hose fell off when it was running rough at first. Didn't smell of fuel, but it was wet.
|
|
VERY interested in MAF/MAP...I think that could be it if tuning doesn't do it. Inch-by-inch, to check the wires, too...I sorta did for hoses and vacuum lines...but maybe not as close as I should have.
PS- I DID find a hose that was dangling, it wa sconnected to something directly below the battery...any idea what that would have been? THe hose fell off when it was running rough at first. Didn't smell of fuel, but it was wet.
