DubbayoC

i put a s4 block in a s5 vert. now it will start but, wont hold idle. ive replaced most of the rubber vac lines and am pretty posiitive everything is hooked up right. i've even taken everything down to the the rats nest to inspect for leaks. i found none. there is one electrical plug that bothers me on the wiring harness. its right next to the water thermo senosr plug. does it go anywhere? also i see alot of bubbles in my oil metering lines. whats goin on? am i not able to run a s4 short block in a s5?

JDuncan

iTrader: (3)

Similar problem here with an S4 block in S5 automatic. I have yet to figure it out. Everything seems in perfect order. Car will not idle. It can be kept alive by throttle modulation and that is it. It will try to run right under load though.

ajsuper7

you need to put the right engine in, the ecu was not made to drive a s4 block, only s5. why take a step backwards anyways?

rx7jones

get a s4 ecu...

DubbayoC

the only thing that is a s4 is the short block everything else is a s5 waterpump housing, alt, intakes, vac rack, etc.... s4 ecu??? i can try that but i dont think it'll work since s4 ecu is low impedence. the reason a s4 block is goin into the s5 is because the original engine blew a water seal and i happen to have this s4 engine available. any other ideas? huge vac leak?

DubbayoC

btw i run a s5 block in my s4 with no problems at all

RotaryForce13B

You can run a S4 Block in a S5 all day long!!!!! I had one in my s5 for years! The problem that you are experiencing is a big vacuum leak and its going to take a few hours to fix. OK, what you need to do is remove the intake then look at the block where the lower intake bolts up to the block you should see a freeze plug on the intermediate housing below the primary injectors. That is the problem! The S5's dont have this freeze plug and the S4's intake was made to go around it. So, what is actually happing is that the S5 intake is hitting the bubbled out portion of the freeze plug. Its not a problem all you have to do is tap on the freeze plug to dent in the bubble (It only has to dent in like a couple of thousands of an inch so dont beat it cause it might fall in.) get a straight edge and check your clearance as your taping......

That should get you up and running again!

DubbayoC

im on it...thx. check back to see how progress goes.

RotaryForce13B

I sure will!

wozzoom

This is stupid advice. If you don't know WTF your talking about, then why bother posting?


Dubbayoc:
You have a vac leak. When you put the S5 intake on the S4 block, did you grind down the engine at all? The S5 intake doesn't sit flat on the S4 block unless you grind an area back by the firewall.

Let me find a pic.

DubbayoC

freeze plug? i got the intake off. whats a freeze plug look like? you mean the vac nipple in the middle of the lower intake manifold?

no I didnt grind anything off just sanded the mating surface.

wozzoom

Like this:

wozzoom

I don't know what freeze plug they are talking about. the only thing that needs to be ground down/modified is in the picture above...

If you don't remove that metal, then the VDI intake will not sit level on the lower intake manifold. Hence, you have a big vac leak.

DubbayoC

oooooooh

wozzoom

Have fun with the grinder! The car will idle better when you get it back together.

DubbayoC

that makes sense.....grinding away right now

cwsttu

lol thats almost to funny..... hell if i had not read that write up i wouldnt know to grind it all down either... good luck with it... keep us posted

DubbayoC

ohhh crap......first i dont think i grinded enough away. second, i think i popped the motor.
welp......got class now. guess ill do a compression test when i get back.

wozzoom

I'm not even going to ask how one would pop the motor by grinding...

RotaryForce13B

I didnt have to grind anything at all on my block.......hummmm thats strange!

RotaryForce13B

Dubbayoc

I am working out of town and dont have any access to any of my housings to take a picture of. Can you take a picture where the intake bolts onto the block (if at all possible) and ill show you what I was talking about.

RotaryForce13B

I found a picture. This is my S5 block thats in my 90 GXL but it will show the location of the area I was talking about. Now that I think about it. I dont think its a freeze plug at all. I have no idea why that stuck in my head. But it is a dome shape that is below the primary intake ports. Ill try to find a better pic.

DubbayoC

k im back.....PHEW! compression is good. dont ask why i thought it blew. guess ill rip apart the intake again and start gring more stuff.

DubbayoC

aiight.... its all back together but it still wont hold idle.

RotaryForce13b, it would be great if you could find a different pic. i have no clue what you are talking about...off to work..will check post when i get back. thx again for your guy's help

DubbayoC

ehhhh bump...