Hi y'all...

As the title says,seems i've got this 3800rpm hesitations after :-

1.servicing all the 4 injector.

2.change the all NEW :-
A. water temp sensor located behind the water pump housing.
B. water thermo sensor located right below corner radiator.
C. air intake temp sensor.
D. Front fuel filter.
E. Differential mount.

3. correcting the s5 alternator wiring due to battery discharging.leaving the s4 B/W wire alone unconnect,then connecting the S to the B+. No discharging afterwards.

All seems to be working fine except the 3800rpm hesitations appear after all the work done in 4 days time.As reading AC suggestions,it's all been done.i'm also trying to connect a new boost sensor ground successfully,then the engine just cranking without starts,disconnect the ground,there yaaa go....the engine immediately starts.grounding it again,no start,disconnect it again...yes!! It start.so am leaving it disconnect.

So....what's wrong with it?which to check?all work been double checked before finalizes & after.

Any inputs will be appreciated!!

 

There are 4 wires to the boost sensor and you are grounding the "wrong" wire. You are obviously grounding the Vref wire which should have 5 volts w/key to on. So, go to the sensor w/key to on and measure the voltage of the wire you are grounding and you will see that it has 5 volts to it which tells you that you are not adding an additional ground to the ground wire but to the Vref wire (wrong). W/key to on one wire will have 12 volts (B/W wire). One wire will have 5 volts (Vref wire). One wire will have close to 3.5 volts (Brown/Red wire). The final wire will have 0 volts because that is the ground wire.

 

Any chances you might know the ground wire colour sir?

Thanks

 

For one you did not state the year. Secondly, a multimeter will absolutely tell which wire is the ground wire. If you don't happen to have a meter then you could do it by process of elimination for you know it's not Black/White or Brown/Red or the wire you are currently grounding from, which the Vref is Brown/White.

88's use a Black wire for the ground but if you have an 86 then it is a different color such as a Brown based color. So, it's not Br/R or Br/W but the other Brown wire I would suppose.

 

Sorry,misplace my multimeter years back,mine's is 88 s4 sir.

Thanks sir

 

Then the solid Black wire would be the ground (not Black/White).

 

Honestly, if your going to be doing work on these cars, or any car, buy another one, you'll love yourself

 

Probably will on the next wish list...btw i'm reconnecting the boost sensor ground already,engine starts finally!!

But haven't test it for a run,will be update later on how it'll do.

Huge Thank you for all the reply sir.really appreciate it!!

 

Ok,did run her up,sadly...the hesitation do still exists.
What could be possibly wrong?
Do i need to connect the B/W s4 alternator wire to something like grounding it or what since it's an ignition source for the ecu?

 

ecu wiring loom , about one foot out from the plug.. ecu earth, instrument earth, shield earth

they all bundle together with a brass crimp

resolder the crimp,. add an earth strap to it.. bolt it to the ground that is for the ecu cover plate

nearby in the loom is another brass crimp.. injector power .. resolder and reinsulate this crimp

 

Where is it located sir?in the engine bay or somewhere inside the ecu area?

Thanks.

 

A must have!

 

under the ecu cover plate , just out from the main plug

 

The harness to the ECU. About a foot away from the ECU plugs. And if this doesn't help then you need to make sure the secondary injector plugs are secure to the injectors as a loose plug could also cause your problem. And a wire pulled back within the plug could also be problematic.

 

Merry Xmas and happy new year to all the rotor heads all around the world!!

Just an update for my 3800rpm hesitations problem,already did reground the ecu ground harness plus added an extra 3 new ground points,sadly the hesitations do still exists.

I'll guess I'll have to recheck the secondary injectors plug,gotta take the long shots here....

Anything that i should be looking at before pulling out the TB?

Thanks all and happy new year!!!

 

You might want to check the boost sensor. The Brown/Red wire should read 3.5 to 4 volts w/key to on. And the secondary injectors are accessible w/o taking off a manifold.

 

Also check the ground under the TB, in the middle of the rat's nest, once you're in there. The ground I'm talking about uses one of the mounting points for all the rat's nest lines.

 

Update:

Finally purchased the multimeter to checkout the boost sensor.gladly all are within spec.

Rewired the s5 alternator S wire and splicing to the white egi fuse wire (closest to the engine side).

Do a bit adjustment to the tps since it's been reading +1.5 more volt than spec.

Haven't test her for a run,maybe later do so.will make an update after.

Thank you for all the inputs that been given.thanks again all.

 

Tested for a run....the hesitations still exists!!was it the injectors clogged after been serviced?

Or maybe the oem s4 b/w alternator wire that left unconnected needs to be connected to something?

 

The plug w/two wires connected to the S5 alternator has a W/B wire and a B/W wire. The B/W wire from the alternator runs to a fuse in the engine fuse box which is supplied w/constant voltage. The original wire to the alternator which is B/W wire connects to nothing.

W/respect to the injectors you need to make sure the plugs are secure to the injectors and that both wires are not pulled back within the plug because if either wire is then there will be poor or no contact between it and the injector. W/key to on the secondary injector pins at the ECU should have 12 volts. If there isn't 12 volts then there is something up at the injector plug. Pins 3H (Light Green/White wire) and 3F (Light Green/Red wire).

And I can't remember if you stated whether the engine will free rev fine when in neutral or not?

 

the alternator wiring seems to be all correct as per suggested.
about the hesitations,the engine won't revs past the 3.8k rpm even in neutral.
Just Now i'm having trouble to start up the car after being washed.seems the starters won't even spin at all.jump start it then it starts.but all my warning lights lids up after start,then back to the normal state(no warning lids).
However as i move the car to my garage,all the warning lights lids again,it seems that if i press the accelerator pedal,on 800rpm,the warning lights lids up.below that,no lids.

 

Could it be all the problems that i'm having is due to a bad alternator symptoms?(3.8k hesitations & the warning lights)

 

The warning lights would come on when the alternator is failing. Whether or not that is causing the reving problem is debatable. The output wire of the alternator should read 14 volts. You also might have a clogged exhaust system. You also might have an AFM that is problematic.

 

Did rebuild the alternator,install it...start it...bammm...warning lights problem solved!!

Engine idling fine for about 3 min...then something strange happened.it seems to be bogging...sounds like running with only just 3 cylinder.

Turn off the engine...change the spark plugs with my spare sets (used for about less than 2k km & cleaned).

Start her up....same idle as before.
Going to the engine bay,wiggling at the spark plug wires area,no changes.
Now Moving my hand to the coil area...
Leading side..both ok...
Trailing side....BBBBZZZZZTTTTT....damn it....it electrocuted me hand for a f##kn 3 seconds...hahahhaha....

So...what do you guy's think?what's the problem now?was it :-
A)faulty spark plugs.
B)faulty spark plugs wires.
C)faulty ignition coils.

Thanks y'all!!

 

More on the obvious side but have you checked your auxiliary port actuators to make sure they're not seized?