Hesitations under load
 

Hi I have a Problem I cant solve.

Last summer I got a FC NA (european spec) to do a TII engine swap.
I had a complete TII in spare parts in my garage I just needed a chassis ^^

So over winter I swaped the whole drivetrain and the right hand engine harness.
The left one is sadly different on euro NAs so I did the wiring of the CAS and coils myself.

Now the car is idling fine but when driving I have hesitations and the get more with more load.
Under boost they get even worse so its not just the 3000rpm hesitation.
So I suspected the fuel system and changed the fuel filter and put a walbro in.
I also swaped the injectors primary to secondary but it didnt change a thing.

Does somebody have a clue?

-Patrick

I was going through the same symptoms for a few months until i did a complete check for vacuum leaks. I found a few open vacuum nipples on the manifold. There are a few in the back of the UIM by the throttle body, another on the front passenger side and another in the lower front. I'm sure there are more, just check out a service manual and see if that's the same thing happening to you.

Hm...I did a leak test on the intake with pressure..
but Ill double check that just to be sure

fuel lines on the correct way? think n/a and t2 are opposite. just read a thread earlier today where the guy made that mistake and had a similar hesitation.

Makes me think a bit.
I know that on US swaps the N/A cars had a chassis wiring change that was needed for the boost solenoid.
This wire was supposed to lead to the "new" boost solenoid instead of the old PS.But it stayed the same on the car but different at the ecu and connector.
The old N/A Power steering wiring was incorporated into the wiring and when you did the engine swap the Wire would cut or vary power somehow to the ecu..

Now,If you look at the pin outs of the Ecu you can see the difference..I "think" it is Pin 3D or 3R..something like that.(N/A pin out)
You needed to cut this wire at the Ecu connector so it wouldn't vary the power when you turn the car,or put the car under load.

Again,I am not sure if it has anything at all to do with your situation but you may want to read up on it.
If it has nothing to do with it then you have just learned some more useless info about these cars..lol!

Smoke test everything . I've pressured before and did find leaks but when I smoked the system I found a few . Are you fmic or tmic ? Check voltage at pump if possible while running and someone in back with a probe lol . Also make sure injectors are crossed and your running on secondary first . Just a few that popped in my head

Have you checked the condition of your spark plugs and wires? I recently had a similar problem on my '88 N/A. The plugs were done.

Tps.

Thanks for all the tips ! :D
So I went to the car and first checked the fuel lines, but sadly I got them already right :P
Then I started the engine and checked for vacuum leaks, but everything seemed fine.

So just because I had long struggles with ignition timing I checked that again,
and saw that timing was to late....L1 behind red mark, maybe 20° to late
So I fixed that and put L1 on yellow mark.
Dont know why but when setting up the engine, timing was always different.

Isnt timing when cranking the same when idling ? ( L1 on yellow mark )

Now the engine revs to redline :D

-PatrickT

The problem came back so maybe it wasnt just the iginition timing :(
So I went on and replaced everything on the fuel system,injectors, tank itself and filter again because the tank was a bit dirty...
And it didnt change a thing :((

So yesterday I connected my boost controller to the injector wire at the ecu to monitor the injector duty.
The duty jumpes up and down and with this you can feel the engine having full power when its up and not full power when it is lower.

Watch this in a video I made:
The drop from 60 to 30% is when the secondaries come on.
On the right side I had the AFM signal monitored to see if there is a connection, but i doubt it.
I also had the AFM replaced with an old one with no effect.

So what else can cause these mixture jumpes from the ecu?
I know the AFM is the main factor for injection timings, but there are other effects like temp and so


-PatrickT