Help me do some diagnosing...
10-03-05, 08:23 PM
#1
...94% correct.
Thread Starter
Help me do some diagnosing...
The car
1988 TII
Newly rebuilt massive streetport
Rebuilt stock turbo
2.5" Racing Beat downpipe, 2.5" midpipe to single SS muffler
CAI
Turbo XS BOV
3 row Koyo radiator
FD 120 amp alternator w/ dual-belt pulley
HKS Type 0 Turbo Timer
No air pump or accessories
No rat's nest
sub-zero system removed
BAC was disconnected and blocked off except for the air pipe in front of the turbo
fuel cut defenser
Starting up, she doesn't idle...will not. I have to get her up to about 100* before she'll even try to hold an idle on her own. I set the idle to 1100rpm...that helped.
When you're driving, there's periodic stumbles at gradual accelleration and and steady driving.
Going to WOT results in a bog then a slow climb in rpm...at about 4000rpm or so it smooths out but it's nowhere near as fast to rev as my experience tells me RX-7's should.
I've checked for vacuum leaks, didn't find any. I do know that my injectors leak...there's caked grime around the injectors themselves and after the car has warmed up and shut down, you either have to do the deflood proceedure or wait for her to cool off.
Any suggestions?
1988 TII
Newly rebuilt massive streetport
Rebuilt stock turbo
2.5" Racing Beat downpipe, 2.5" midpipe to single SS muffler
CAI
Turbo XS BOV
3 row Koyo radiator
FD 120 amp alternator w/ dual-belt pulley
HKS Type 0 Turbo Timer
No air pump or accessories
No rat's nest
sub-zero system removed
BAC was disconnected and blocked off except for the air pipe in front of the turbo
fuel cut defenser
Starting up, she doesn't idle...will not. I have to get her up to about 100* before she'll even try to hold an idle on her own. I set the idle to 1100rpm...that helped.
When you're driving, there's periodic stumbles at gradual accelleration and and steady driving.
Going to WOT results in a bog then a slow climb in rpm...at about 4000rpm or so it smooths out but it's nowhere near as fast to rev as my experience tells me RX-7's should.
I've checked for vacuum leaks, didn't find any. I do know that my injectors leak...there's caked grime around the injectors themselves and after the car has warmed up and shut down, you either have to do the deflood proceedure or wait for her to cool off.
Any suggestions?
10-03-05, 09:14 PM
#3
...94% correct.
Thread Starter
the adjustment screw on the BOV? How do I test the BOV to see if it's malfunctioing?
edit~ I don't see an adjustment screw on my BOV. Where should it be?
Who makes "Turbo XS" BOV's anyway?
edit~ I don't see an adjustment screw on my BOV. Where should it be?
Who makes "Turbo XS" BOV's anyway?
Last edited by Makenzie71; 10-03-05 at 09:17 PM.
10-04-05, 01:29 AM
#6
(_8(|)
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from the couple people ive seen with turbo xs bov's they seem to have some problems with em, maybe you should look into a different one? Im in no way sayingthey are bad (ive never owned one). Sorry i cant help with the adjusting, but at least its a start? 
10-04-05, 01:38 AM
#7
sounds like a vac. leak (at least partially). I assume you checked by spraying carb cleaner around the motor?
Have you checked your TPS?
Compression? (might as well)
I know that disconnecting the thermowax/emissions stuff makes it hard to start cold (i.e. give it gas for a while)...
Since you say it starts 'smoothing' out at about 4k, maybe your primary injectors are gummed up or something (wheras your secondaries are fine....?)
Is your twin-scroll hooked up correctly? (this will cause slow boost response in s4's).
Re-reading, those "slight stumbles" at partial throttle (like a jerky/boggy feeling) are likely due to a TPS on it's last legs...
Have you checked your TPS?
Compression? (might as well)
I know that disconnecting the thermowax/emissions stuff makes it hard to start cold (i.e. give it gas for a while)...
Since you say it starts 'smoothing' out at about 4k, maybe your primary injectors are gummed up or something (wheras your secondaries are fine....?)
Is your twin-scroll hooked up correctly? (this will cause slow boost response in s4's).
Re-reading, those "slight stumbles" at partial throttle (like a jerky/boggy feeling) are likely due to a TPS on it's last legs...
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10-04-05, 01:46 AM
#8
...94% correct.
Thread Starter
Originally Posted by eriksseven
sounds like a vac. leak (at least partially). I assume you checked by spraying carb cleaner around the motor?
Have you checked your TPS?
Compression? (might as well)
I know that disconnecting the thermowax/emissions stuff makes it hard to start cold (i.e. give it gas for a while)...
Since you say it starts 'smoothing' out at about 4k, maybe your primary injectors are gummed up or something (wheras your secondaries are fine....?)
Is your twin-scroll hooked up correctly? (this will cause slow boost response in s4's).
Re-reading, those "slight stumbles" at partial throttle (like a jerky/boggy feeling) are likely due to a TPS on it's last legs...
Is the S4 NA and TII TPS the same? I have several S4 TPS's (or is it's TPI for plural?...I'm a dork)...
10-04-05, 02:01 AM
#9
About the twin-scroll; on a s4 turbo, half of the exaust is 'blocked' by a little door that opens at like 2800 RPM's (I think). It's controlled by an actuator ran off of vac pressure. If the twin-scroll ISN'T hooked up the car will be a little lazy until the boost finally builds... If you're not sure if it's hooked up etc. it's definitely worth looking into. When it's hooked up correctly, the low-end response is a lot better.
10-04-05, 02:05 AM
#10
...94% correct.
Thread Starter
Originally Posted by eriksseven
About the twin-scroll; on a s4 turbo, half of the exaust is 'blocked' by a little door that opens at like 2800 RPM's (I think). It's controlled by an actuator ran off of vac pressure. If the twin-scroll ISN'T hooked up the car will be a little lazy until the boost finally builds... If you're not sure if it's hooked up etc. it's definitely worth looking into. When it's hooked up correctly, the low-end response is a lot better.
10-04-05, 02:23 AM
#11
Ya', jerky would be a bad TPS.
On the s4 turbo's, one of the exhaust 'runners' is smaller than the other. This is covered by a small 'flapper door' (to help spool-up). At a certain RPM/vac. pressure the door is opened by a little actuator (like the WG).
If the 'runner' isn't ported out (to match, for example the s5 turbo), you won't be getting full spoolup as early (although max boost etc. is uneffected).
I'd compare it to having your 5th and 6th ports disconnected on an N/A.
On the s4 turbo's, one of the exhaust 'runners' is smaller than the other. This is covered by a small 'flapper door' (to help spool-up). At a certain RPM/vac. pressure the door is opened by a little actuator (like the WG).
If the 'runner' isn't ported out (to match, for example the s5 turbo), you won't be getting full spoolup as early (although max boost etc. is uneffected).
I'd compare it to having your 5th and 6th ports disconnected on an N/A.
10-04-05, 02:29 AM
#12
...94% correct.
Thread Starter
alright...I'm going to wire me up a couple of LED's when I get home and set the TPS. I haven't found a good diagram of the plug and terminals I'm supposed to use...any help with that?
10-04-05, 10:31 AM
#13
andrew
Join Date: Mar 2005
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check the leading coil my car did the same thing when that went, almost felt like a blown motor. If not that maybe AFM oh and like what was said above, check twin scroll
10-04-05, 04:51 PM
#15
Banzai Racing
Those are terrible compression numbers even for a fresh rebuild with a "massive" port.
It should increase some with a proper break-in but you will be lucky to see 90-95 which is still weak.
It sounds like you need to check a few different things.
Water thermosensor - green sensor on the back of the water pump housing- if it is running rich
AFM (common failure item) & turbo inlet duct- for cracks, also very common failure area
Intake air temp sensor can also cause it to start very hard and have a bad idle.
It should increase some with a proper break-in but you will be lucky to see 90-95 which is still weak.
It sounds like you need to check a few different things.
Water thermosensor - green sensor on the back of the water pump housing- if it is running rich
AFM (common failure item) & turbo inlet duct- for cracks, also very common failure area
Intake air temp sensor can also cause it to start very hard and have a bad idle.
10-04-05, 05:48 PM
#16
...94% correct.
Thread Starter
Originally Posted by BlueTII
Those are terrible compression numbers even for a fresh rebuild with a "massive" port.
It should increase some with a proper break-in but you will be lucky to see 90-95 which is still weak.
It sounds like you need to check a few different things.
Water thermosensor - green sensor on the back of the water pump housing- if it is running rich
AFM (common failure item) & turbo inlet duct- for cracks, also very common failure area
Intake air temp sensor can also cause it to start very hard and have a bad idle.
It should increase some with a proper break-in but you will be lucky to see 90-95 which is still weak.
It sounds like you need to check a few different things.
Water thermosensor - green sensor on the back of the water pump housing- if it is running rich
AFM (common failure item) & turbo inlet duct- for cracks, also very common failure area
Intake air temp sensor can also cause it to start very hard and have a bad idle.
I've checked the intake plumbing for leaks and I don't know how to check the AFM out. I'll look at the thermo sensor, though, and the intake air sensor.
10-04-05, 06:45 PM
#17
...94% correct.
Thread Starter
did it again...
even 62psi on both rotors at 300rpm. This is by just bolting the guage up and let it pump air to it's max. Levels off between the 50 and 75 marks. Plus the ambient 14.6lbs or whatever....<80psi...
Yes, had it floored.
even 62psi on both rotors at 300rpm. This is by just bolting the guage up and let it pump air to it's max. Levels off between the 50 and 75 marks. Plus the ambient 14.6lbs or whatever....<80psi...
Yes, had it floored.
10-05-05, 10:07 AM
#20
HAILERS
Join Date: May 2001
Location: FORT WORTH, TEXAS,USA
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Originally Posted by BlueTII
85 lbs is not the spec on a rotary engine, 8.5 bar which equals 125psi is the spec. Below 90psi we tell people to start saving for a rebuild.
See page 1-11 of the Factory Service Manual, 1987.
That said, the compression sounds very, very low. Buy new rotor housings on your next rebuild.
10-05-05, 10:18 AM
#21
...94% correct.
Thread Starter
Originally Posted by RETed
Who did the rebuild?
What kinda vacuum readings are you seeing at idle?
-Ted
What kinda vacuum readings are you seeing at idle?
-Ted
Vac at idle bottoms the guage out...I can't remember what that particular number is but I know it's a good one...
10-05-05, 11:04 AM
#23
...94% correct.
Thread Starter
pulling 28lbs at idle (1000rpm or so)
What does that tell me?
Last night I fed her about 16oz of water and then about 12 of barryman's EFI cleaner and she really drove a LOT better, but still nowhere near as powerful as I'd expect a turbo with a large streetport to be. At least now she feels faster than my Bimmer...but not by much.
What does that tell me?
Last night I fed her about 16oz of water and then about 12 of barryman's EFI cleaner and she really drove a LOT better, but still nowhere near as powerful as I'd expect a turbo with a large streetport to be. At least now she feels faster than my Bimmer...but not by much.