Help! SOHC->DOHC swap, idles weird, 3 codes

[mike2016]

Ok i just did the dohc swap and it wont idle good, but it pulls hard and drives good, but it will jerk when i on/off throttle. it won't rev past 6000rpm, it just stop and the intake makes a loud popping noise.

it's a 98 S14 KA running on 92 DOHC Harness + 92 DOHC ECU + 92 DOHC sensors + 92 DOHC distributor...etc

all the junk vacuume lines are removed down to only 1 vacuume line for fpr. checked no vacuume leaks.

It idles perfect for about 5 seconds, then drops so low until it's about to die, then idles good again..then drops.. it just keeps doing this.

** when the idle is dropping , there's smoke come out of the tail pipe, it's unburnt gas for sure, it smells just like gasoline.


timing is checked and but it shouldn't cause the weird idle right ?

ECU pulled 3 codes:

12 - MAFS (I'm using S14 KA MAF, don't have S13 dohc maf)
21 - Primary ignition circuit
32 - EGR system (removed egr, everything)

I thought the S14 KA MAF is the same as S13? the SAFC setting for both MAF are the same at least.

[Ritz S14]

I think it could be your S14 maf. Since the computer is a 92, it expects to see 92 components.

EGR- Did you cover up the egr passages?

Check firing order, and make sure the wires you spliced are soildered.

[nightwalker]

fix your maf first. Then see if you still get the same problems.

[mike2016]

yes i blocked off the egr passages. no leaks.

I'll try to find a 92 maf and try that...


firing order.... i wasn't sure if I installed the distributor right,

I cranked it to set No.1 at TDC, then insert the distributor and line up the marks, the rotor line up with No.1 Coil. is this correct? is it possible I had set No.4 at TDC ?

[240Driver39]

s14 maf will not run right on s13....get an s13 maf

[mike2016]

okay i got a s13 dohc maf and changed it, same thing.

i discovered that the IACV wasn't working, due to a mistake in wiring, but i fixed it and it's working now.

if i disconnect the tube going to the IACV from the intake pipe, the car will idle A LOT better, but it still has that stumble every 5 seconds or so.

or if I unplug the MAF (IACV tube still connected) , the car idles normal.

when the idle drops and bog, it just shoot lots of black smoke out the tail pipe... gas mileage sucks too. less than 180 miles on a full tank of 91. :tweak:

any one ??

[vvtisupra]

don't the 92's run air injection ? would that do anything ? also the vaccuum tube right by the coolant upper pipe if its not hooked up to any vaccuum source will idle super bad

[mike2016]

the vacuume tube by the coolant upper pipe? do u mean the fat big tube that feeds the IACV and the IACV air regulator? if i disconnect the tube the car idles better.... :(