Hello all,

87 S4 turbo with a big street port, T04E turbocharger, FD UIM and TB, and PFC. As the title states I cannot get the damn thing to start. Little back story, turbo blew in the car so I rebuilt the turbo. During the time I found out the real reason why the downpipe was heat wrapped, so I had a buddy help me weld it up. I also changed our a leaking water pump, relocated the battery to the back and installed a much larger, 800CCA/1000CA battery, and swapped out the Lincoln locker for a GXL LSD differential. So the car was running before I did all this work, mind you I've been fiddling with the throttle body because it was not hot starting, and I got it pretty good but not perfect. I had it set to ~1200RPM idle but at start up regardless hot or cold I'd have to hold the throttle or it would die out, I also would have to slightly hold the throttle to get it to start. After running the car with just turbo and no exhaust I played with the air bleed. I read somewhere on here it should be 1/4 to I believe a half turn out from closed so I set it to that. Now this is where I fucked up royal, I forgot how much I was at originally. So anyways I complete the rest of the work and the damn thing won't start at all. I fiddle with the air bleed but no success. I tried fiddling with the other adjustments and still no success. I even bought Chuck's PFC notes and set the throttle body like that and still not damn success. I only have 4 adjustments on the throttle body, the main set screw, the secondary port set screw, TPS, and air bleed. Can someone please help me out as I'm completely lost on what to do.

 

so do you have spark? do you have fuel?

 

Fuel yes, spark 99% sure. It sounds like it tries to fire but doesn't catch. I strongly feel it's related to the throttle body since it was fine until my dumb mitts touched it again aha.

 

have you checked to see if it's flooded?

 

Yes, I've deflooded it just incase multiple times by shutting fuel off and cranking WOT as I have a fuel kill switch.

 

while TB adjustments will certainly effect idle they have little effect as to starting. as has been suggested, spark and fuel should be your primary focus.

 

The TB adjustment actually got rid of my hot start issue almost completely all together, would it have the same effect on cold starts tho? I know it's got fuel I can smell it and hear it. Spark like I said is something I'm 99% sure on. I'll try and pick up one of those inline spark testers and try and verify 100%.

 

That extra 1% will get you every time. Pull the plugs, ground and see if you got spark. Turn it ver some more to get the fuel out. 10 minutes to be sure……and it needs to be done anyway to see if the plugs are toast.

 

The plugs have less than 300KM on them I don't think they'd be toast that quickly

 

The reason you’re not getting many responses is you have not done the simplest and most important things already.

 

Well it was running before I touched the throttle body and now it's not. The only other things that happened in between running and not running besides adjusting the throttle body is I changed the diff and I changed the water pump, both of which won't affect starting. If this just happened out of the blue I'd understand but I'm heavily inclined to believe it's air related as my prior adjustments pretty much solved my hot start issue. I know 100% have fuel and 99% sure I have spark, I can hear it trying to start sometimes but then it dies off.

 

if you had the water pump housing off, and the Coolant Temp sensor didn't get plugged in, that would cause a no start

since you have a PFC you can check it in the sensor check screen. and while you're there you can crank the engine and make sure the ecu sees rpm.

 

The temp sensor was plugged it but was reading 4.99V, it ending up being the pins in the connector so I fixed it and it's reading properly now. Still no start however. I am getting a rpm signal based on the PFC.

 

Finally had some time to work on it, verified I have spark and fuel 100%. Checked every single lead too. So I'm back to air sadly.