89 sidekick 1.6L 2dr 4x4 A/T

[Behringer]

Hi all, 
thanks to everyone who's contributed to this site. It's been super helpful. 

89 sidekick 1.6L 2dr 4x4 A/T

CEL on with Key, off when started. Code 12 when codes pulled.

Vehicle warms up to 180+
Cold start 2000 rpm
Idle drops 500 within 30 sec to 1500 rpm
When warm 800 +- 50 rpm
Load on 950 rpm
Compression 170-175 psi across all cylinders.

New parts

TB all gaskets.
Air filter
Timing belt
Water pump 
Plugs
Wires
Coil
Distributor and rotor 
O2 sensor
ECT 
Oil pressure sensor
Complete exhaust (except manifold)
Vacuum modulator 

First let me say that my rpm isnt completely stable. It fluctuates up and down +- 50 rpm at all times. Using the propane technique I've discovered if I apply propane to back side of EGR (where you push for stall test) the idle increases. I assume this is suppose to be air tight? No other areas see any rpm change with propane applied.

Second issue is, when I put into gear the rpm drops 200-400 rpm and will not recover. With any electrical load (headlights, heater) the rpm increases about 150 rpm.

I was willing to live with these issues until a few road trips have shown I'm getting 18 mpg highway. Other things to consider is I'm running a 2 inch lift with 31's. With stock gearing. From what others have posted this seems to be horrible mpg. 

Anyone have any input? Thanks

[fixkick]

Hi all, 
thanks to everyone who's contributed to this site. It's been super helpful. 

89 sidekick 1.6L 2dr 4x4 A/T

CEL on with Key, off when started. Code 12 when codes pulled.

Vehicle warms up to 180+
Cold start 2000 rpm
Idle drops 500 within 30 sec to 1500 rpm
When warm 800 +- 50 rpm  (normal that is)
Load on 950 rpm (normal see fast idle up  , diode block under dash)
Compression 170-175 psi across all cylinders. very good.

New parts

TB all gaskets.
Air filter
Timing belt
Water pump 
Plugs
Wires
Coil
Distributor and rotor 
O2 sensor
ECT 
Oil pressure sensor
Complete exhaust (except manifold)
Vacuum modulator 

First let me say that my rpm isnt completely stable. It fluctuates up and down +- 50 rpm at all times. that is normal and spec.

Using the propane technique I've discovered if I apply propane to back side of EGR (where you push for stall test) the idle increases.
I assume this is suppose to be air tight? No other areas see any rpm change with propane applied. You assumed correct that EGR is sucking air , vacuum leaks,

Second issue is, when I put into gear the rpm drops 200-400 rpm and will not recover.  (that is wrong) ISC is dead, why can be complex)
With any electrical load (headlights, heater) the rpm increases about 150 rpm.

I was willing to live with these issues until a few road trips have shown I'm getting 18 mpg highway. 26mgh normal, not 18 unless driving 85mph all the time..
Other things to consider is I'm running a 2 inch lift with 31's. (that makes the odometer lie big time it runs slower, the taller the tires and lies on distance and MPG is based on that.

With stock gearing. From what others have posted this seems to be horrible mpg.  i have the correction page here.
named gears. use a hand GPS for distance, and see the here , i think 10% but dont know your rim sizes (circumference is the key fact)

https://fixkick.com/part-time-test.html#SPEED

lots of reasons for mpg low.

https://fixkick.com/MPG.html


Anyone have any input? Thanks

good luck you  and your 89.  if the VIN starts with letter J, they made the first ones in actual japan then later 2cn canada prefixed VIN

[fixkick]

are you sure this car has the A/T ECU,  most of these 89s were stick shifted MT cars.
the ECU tag and vin number full should tell what it had new but what matters most is ECU tag.
US MT is wrong tagged ECU.

[Behringer]

So I checked the Vin and it does start with a J. Ecu # 33920 60A41. Looking at the website it seems this is the correct ecu. I'm a little confused with the ISC. If its activating when there is extra load doesnt that mean it should be working?

[fixkick]

So I checked the Vin and it does start with a J. Ecu # 33920 60A41. Looking at the website it seems this is the correct ecu. I'm a little confused with the ISC. If its activating when there is extra load doesnt that mean it should be working?

the very first cars Japan, CAMI was not open yet, in canada.'
A4 is AT. A3 is MT

yes this ISC is not working, 
if you have vacuum leaks it can lose control of idle
when you shift from park to drive the ECU sees you do that (a pin on the  ecu goes hot)
then the ECU uses aggressive idle controls do to that huge TC load. on the engine.
so sound like your is sticking,  the ISC up to has 2 dangling wires, make sure those connections are ok
and valve cleaned.
on many of these cars, the valve sticks so the owner hides the bad idle buy opening the throttle stop screw.
but how to do that there are 2 modes, parked or in drive.
if you set the idle with the stop screw, at 800 then shift to drive, the RPM falls like rock.
if you set the hot idle in drive (ouch dangerous) to 800 then back to park idle screams. so you are not this case.
this is also done same way with vacuum leaks the close the TV with the idle screw to hide the leak. 
what is odd is why does idle up work 950rpm IIRC, is fast idle.  head lamps, on, blower on heater or defrost or AC onl .


see page 2 for the diode block for idle up
https://fixkick.com/ECU/89/1990-scan-ECU/allpages.pdf

[Behringer]

Thanks for all the help. Took it out and cleaned it again. (Tapped it with a wrench a few times) seems to have started working again. I have a new issue that has arisen during the weekend.

My house is right at sea level. Idle holding 800 +- 50 even in gear now. 950 with load. However while I was hunting change in elevation was dropping my idle alot. At 4000' idle with load was 400rpm. Go down the mountain and totally fine again. Also had issues starting it while at higher altitudes. Usually starts within a couple cranks. Up there about 15 cranks. Any ideas?

[fixkick]

the ISC electric valve opens up as you go to 4000ft. there is less AIR at 4000ft so the valve opens more (the ISC is just and air solenoid modulated by the ECU as an electronic servo)
sure would have issues starting with so little air,so crank the engine over with say 5% (tiny) foot action on the throttle.
the MAP sensor must be working too, this sensor tells the engine the load on the engine using vacuum and at key on tells the ECU your altitude too.
EFI measures all this, and more,
400 rpm is caused by 2 things,
EGR stuck open or dead ISC. (hot engine)

seems your ISC is dead. (many are this old, and the PO previous owner HIDE THAT by , opening up the 1989/90 TV valve by screwing IN the throttle stop screw.
then later notices idle wrong later, the stop screw has no brains behind it so fails. but not hot and parked in out of gear and fiddled with.

in the old days with CARBs we went up to 10,000 feet (ski trips) and idle is too low there so we turned the screw, and also defeated the auto chock or next cold start floods the engine.
your car thinks it is CARB car.
1.3L G13 engine was but not your 1.6L (it is TBI car, and all sensors and actuators must work and yours does not)