hey i just got an 85 200sx, i beleive its doug’s old one, sr blacktop swapped in. the guy i got it off bought it with a blown T25 turbo on it and swapped a T28 onto it. he never put it on the road so it hasnt really been driven. i bought this for a new daily driver and would like to figure out the problem.
here are a list of things done to the motor :
ARP head studs
Cometic metal head gasket (oem bore)
New oem water pump
Nismo colder thermostat
All new steel fuel lines
megan racing stainless steel manifold
megan racing stainless steel elbow
Brian Crower valve springs and titanium retainers
stainless steel braided oil and water lines
30x7.5x3.5 Aluminum bar and plate intercooler
HKS ssqv BOV
circuit sports intake plenum spacer/thermal reducer
AEM tru-boost boost controller
AEM Uego wideband
Exedy Stage 2 clutch
14lbs lightweight chromoly steel flywheel
2.5" Straight exhaust piping, dual tip vibrant black muffler
s13 blacktop rad and shroud
Spiral Cell eliminator battery
Garrett t28 turbo
so it doesnt hit any boost until like 5000rpm, i have not have any time to do much investigating yet, im curious what it could be? im wondering maybe an exhaust leak pre-turbo? or maybe some boost leaks in the intercooler piping.
Im new to the whole sr/ turbo thing and any help would be appreciated!
Hole in your exhaust Mani, gasket leak, waste gate stuck open(good poss!) I don’t think intercooler piping would be off, or else it would run rich as a pig. Unless you see that on your wide band…
Check your waste gate first. Then leaks. Then check the turbo, broken compressor wheel, cracked hot side, stuff like that. Check to make sure the boost controller is working properly.
If its a wide band, at idle it should bounce around 15. Cruising around 14.6. At WOT (wide open throttle) it should drop to 11.3 or 11. That’s safe. Anything above 11.6 at WOT is dangerous. The lower the number the more fuel it’s reading, the higher the number the more air it’s reading. U want more fuel with a boosted car. To much air is baddddddd and causes detonation or heat. Causing engine failure. But if it’s mainly stock you shouldn’t have that issuer unless There is a boost leak.
The waste gate u can grab and pull on the actuator arm. Try and move it freely. If you can push it towards the firewall about an inch then it’ll be fine. If u push it only a little bit it could be seized. But best to find out were it is is to take off the turbo elbow and inspect the turbine and the waste gate door is right there.
If he’s not building boost until 5000RPM on a T28, AFR has nothing to do with it. There’s a leak somewhere. The wastegate typically seizes closed, not open, so chances are low there. Start by checking for pre-turbo exhaust leaks, and more specifically boost leaks. I had a pinhole in the vacuum line to my BOV one time, and I experienced the same problem. No boost until 4000RPM+, pulled the vac line off the wastegate and I was building TONS of boost, looked around a bit more, found a tiny pinhole keeping my BOV from sealing shut.
U can tell if there’s a boost leak after the turbo cause the air registered with the maf isn’t reaching the motor causing it to run rich. Ur afr might read that. I’ve had waste gates stuck open, and it killed boosted until there was enough exhaust to even spool. But it could be a vacuum leak dealing with the waste gate. But I don’t think it’s a boost leak After the turbo.
alright guys ive done few things now any have the boost buidling at the right time now. but it still doesnt seem to pull very hard at 3000rpm even tho its at 9psi of boost. it will get to 9psi around 3000 and stay there but wont pull hard until 5000rpm still.
my AFR is reading 17+ at idle and about 13 at WOT but seems to be all over the map, sometimes a little richer (where its suposed to be) but for the most part wayyy too lean. Could this be my problem??? i know it is dangerous to run like this.
i am looking into an SAFC as a cheap quick fix to richen it up so i can get this thing on the road because i currently am without a vehicle. any help appreciated!!
---------- Post added at 09:12 PM ---------- Previous post was at 09:12 PM ----------
alright guys ive done few things now any have the boost buidling at the right time now. but it still doesnt seem to pull very hard at 3000rpm even tho its at 9psi of boost. it will get to 9psi around 3000 and stay there but wont pull hard until 5000rpm still.
my AFR is reading 17+ at idle and about 13 at WOT but seems to be all over the map, sometimes a little richer (where its suposed to be) but for the most part wayyy too lean. Could this be my problem??? i know it is dangerous to run like this.
i am looking into an SAFC as a cheap quick fix to richen it up so i can get this thing on the road because i currently am without a vehicle. any help appreciated!!
13 is dangerous. Should be a tad over 11.
9psi is safe tho.
If its pulling 9psi at 3000 that’s good.
But it’s to lean. Do u have a fuel pressure regilator
I’d try an adjustable. Or but a fuel pressure gauge to try and see what psi it’s at. And the one thing I didn’t see on your list was a Walbro 255 or an aftermarket fp.
With a Walbro my fuel was around 34 to 40 psi with no boost. As soon as the car hit boost it exploded to around 65 to 70 psi. Which is a lot but it’s safe. I don’t think the fuel pump is strong enough.
Well, you’re probably still under fueled, but knowing it has aftermarket cams, I’d check to make sure your cam timing isn’t out either, that’ll fuck with your power curve and change when your boost comes on.