94 Pontiac engine in Sidekick!

[Zackman]

Dear Fixkixk:
You may recall that I was struggling with installation of an engine in my son's Suzuki a few months ago. Anyhow, I finished the job in February. and the car has been running since, but somewhat roughly. I tried to check every possible thing to improve the performance, but I cannot seem to improve it anymore.

Today, I checked the engine VIN (which is 2CGBJ18UXR6903914). The search states the engine belonged to a 1994 Pontiac Sunrunner!

The question I have is that whether the rough running issue might be due to incompatible ECUs? would that be an issue?

I should note that the car starts beautifully, on the first crank. The engine compression is also quite reasonable, a minimum of 155 psi in each cylinder.

Your expert input would be much appreciated!

Regards,
Zackman

[fixkick]

Hello: Mr.Zackman

its it misfiring? if yes, under what conditions
hot , cold engine or both?
idle, racing n neutral, or driving or only up hills or only accelerating?
G16a 8valve (u code? by gm)
are the flash codes running 12s? Diagmode jumper.

Dear Fixkixk:
You may recall that I was struggling with installation of an engine in my son's Suzuki a few months ago. Anyhow, I finished the job in February. and the car has been running since, but somewhat roughly. I tried to check every possible thing to improve the performance, but I cannot seem to improve it anymore.

Today, I checked the engine VIN (which is 2CGBJ18(U)XR6903914). The search states the engine belonged to a 1994 Pontiac Sunrunner!

The question I have is that whether the rough running issue might be due to incompatible ECUs? would that be an issue?

I should note that the car starts beautifully, on the first crank. The engine compression is also quite reasonable, a minimum of 155 psi in each cylinder.

Your expert input would be much appreciated!

Regards,
Zackman

[Zackman]

Hello: Mr.Zackman

its it misfiring? if yes, under what conditions
hot , cold engine or both?
idle, racing n neutral, or driving or only up hills or only accelerating?
G16a 8valve (u code? by gm)
are the flash codes running 12s? Diagmode jumper.

Dear Fixkixk:
You may recall that I was struggling with installation of an engine in my son's Suzuki a few months ago. Anyhow, I finished the job in February. and the car has been running since, but somewhat roughly. I tried to check every possible thing to improve the performance, but I cannot seem to improve it anymore.

Today, I checked the engine VIN (which is 2CGBJ18(U)XR6903914). The search states the engine belonged to a 1994 Pontiac Sunrunner!

The question I have is that whether the rough running issue might be due to incompatible ECUs? would that be an issue?

I should note that the car starts beautifully, on the first crank. The engine compression is also quite reasonable, a minimum of 155 psi in each cylinder.

Your expert input would be much appreciated!

Regards,
Zackman

---

Dear Fixkick:
No, there is no backfiring, or bad codes. It just sounds rough. I also think the engine is burning oil. It just sounds very rough running, and does not feel the same way it was before changing the engine.

I checked the eBay yesterday, and according to sellers of ECUs, the ECU of 94 Sunrunner is the same one that in 91 Sidekick (apparently).

So, I am conclude that the engine is just tired and not very good. What amazes me is the compression reading I got, which does not match what I am seeing in terms of engine performance!
Regards,
Zackman

PS. The oil idiot light comes on after the engine gets warmed up. I have bought a oil pressure gage that I will install today. FYI, I paid more ($20) to get the proper union from BSPT to NPT that I paid for the gage and the three unions that came with the gage ($15) - absurd!)

[fixkick]

91 Sidekick JX, 8V, S. Carolina Car, 2 dr, 3 speed Auto Trani, Halifax, NS, Canada

Dear Fixkick:
No, there is no backfiring, (that is something else, backfiring)
or bad codes. (code 12 or dead , no response from ECU? using the DLC jumper wire?)
It just sounds rough. that is misfiring, most times just needs a tuneup, sparkplugs, wires, cap rotor.
might be just a simple damaged spark wire, id put in BOSCH mag wires.... for best long service.

I also think the engine is burning oil. (if the spark plug tips are not turning black or oil soaked, its ok for now) running 10w-30 oil?)

It just sounds very rough running, (and is misfiring) and does not feel the same way it was before changing the engine.

I checked the eBay yesterday, and according to sellers of ECUs, the ECU of 94 Sunrunner is the same one that in 91 Sidekick (apparently).
the ECU has a part number, most have a 56Bxx suffix, only this matters, who knows whats there after so many years.
I'd bet it is not the ECU, id be all over spark quality first... a full 60k tunup,
there are no sunnrunners ECU, only Canada ECU. are you in Canada.,

So, I am conclude that the engine is just tired and not very good.
What amazes me is the compression reading I got, which does not match what I am seeing in terms of engine performance!
cold compression is near 150,
8v does 150 cold and 170 warm or hot. all do, at sea-level... this is a bench mark , standard, id say yours is ok, if done cold and now know
you are near sea-level.... < 1000feet.



Regards,
Zackman

PS. The oil idiot light comes on after the engine gets warmed up. (not a good sign the sender can trip at 3psi, so, that is bad, what oil is there 10w-30?) or OMG 0W?
I have bought a oil pressure gage that I will install today. (id worry this to death, 3sp is going to starve the cam.... and rods) the cam runs on a 0.050" orifice feed, gallery in head, "TINY"
gallery pressure, :
this engine will do 55psi, cold engine cranked, with spark plugs removed, (this is a test i do even engine on a pallet, and compression next) saves me wasted 8hr labor.... that....
FYI, I paid more ($20) to get the proper union from BSPT to NPT that I paid for the gauge and the three unions that came with the gauge ($15) - absurd!) (cars with BSPT fittings, are a pain, there is no , other way, besides risk,,,, ) its the only non ISO screw/pipe on car,, so... pain.
[/quote]



you are correct compression is first.
then spark, if spark bad , well combustion ends or misfirse
last is fueling, that being rich will cause, misfire.

1: flashes 12s?
using this method.
a jumperclip inserted in the DLC< connector next to battery, 4 pin or 6 pin , is shown here,
must flash 12s.. keyon, then 12s running,,,,
http://www.fixkick.com/CEL/DLC/DiagJump.html

it must flash, not be dead, lamp.!!
off my ECU page are all numbers, (no secrets on this topic, no more guessing)
http://www.fixkick.com/ECU/EPC-ECU96-98/...9-95NA.pdf
market codes
03 is usa fed
33 is usa calif
28 is canada.
in Canada the also have gray market cars, then,,, (from anywhere) only the numbers on ecu matter, or body of car chassis tag matters.
8v only (IS YOURS G16A) would be nice to know what you are driving.. whats under hold first.
56Bxx is the suffix, all prefixes are same (56b means 8valve engine TBI)
all 91s were 8v.
I will now read the full canada listing for 91./94 8v. ecu.

ALL 1991 ecus, are 56B30 mt and B40-a/t (usa and canada) all are. same, matching transmission all in N. AMerican, (canada too) this year.
1994 is different, (in usa smog reasons)
Canada only market code "e28" cars, run 3 ecu. 56B all are... 8v. (sunrunner is just tag sticker from GM)
B90,MT, 2doors,
b70,AT, 4doors (bingo you) 56B70...
B80,AT, 4doors.

in usa, the same 8v engine runs. different ECU, for SMOG reasons
B51, E3,8v, 2dr, m/t , or 56B61 , A/T, so the USA ECU is B61 and yours is B70.... all for smog reasons, there are 100s of ECU world wide.
the 4door here are all 16v so , not applicable to topic.

there i covered, 3 markets and 2 years, and only 8valve engines.

what matters is the numbers stamped on side of ecu, only that matters. and its matching harness, (VIN code tells this)

so, is the front crank pulley bolt , 17mm deep wall socket fits it , tight and fully at 94ft./lbs or loose.
is the cam belt fresh? this is first on all new (found) engines.... first things first... then compression....
is spark timing landing on 5 degrees, or as the hood sticker shows. 5,deg, BTDC? using a timing light and the freeze jumper.
http://www.fixkick.com/IGN_timing/IGN-FREEZE.HTML


back to ECU.
some have bad caps . type ECU in my search box.

what if ECU is wrong suffix number.
well if you mix calif and fed, you get code 53 error, (flashes that)
or EGR fails Code 51.
it wont misfire, only the EGR systems vary.
if you mix 4dr and 2dr, a minor power loose, ive never felt it... but the ECU is tuned for car body MASS.
4dr weighs more that 2doors.


if running any 91 ecu, its more forgiving, less, smog codes.... that is all you will notices, not misfiring, not ever.
But in all cases all engines, EGR must be closed at idle.

that rough sound, is actually misfiring, with attendant loss of power, and engine shacking ,and felt large vibrations.
all that is called misfiring, (it's bad combustion, in 1 or more cylinders. for sure)
bad spark is top contender ,...(good engine) spark wires fresh, BOSCH MAG wires, gaps at .028" not the silly NGK factory , 0.045" EVER !
never run carbon wires, they break so easy, use MAG< wire from Bosch, NKG, or any top brand that are MAG. wires.
the spark on this car is weak, by todays standards and having the best wire set is a win, in all cases,.
also reading spark tips.
are they?
1: black (carbon)
2: oil fouled (brown) or dripping in oil.
3: gas soaked, or dripping gas>?
4: white/cream, tan or dry> (good)
5: green with antifreeze?
6: look damaged?


does it flash code 12s on demand running? it must, (not dead lamp, not stuck on) it flashes. the CEL on DEMAND (by you)

what isnt it
its not vacuum leaks, on a 8v leaks cause too fast hot idle (can) but the MAP sensor must not have a clogged, hose or cracks on it hose. FIRE wall MAP sensor,
is your hot idle at 800 rpm.?

does the misfire happen
cold engine
hot engine
both?
or only moving> if yes, when, under what conditions,?

Backfire, is not misfire, well it is but 10x worse. back fire to air cleaner is bad timing, grossly bad. (cam timed wrong, distrib, or both)
Backfire to tail pipe end is , called muffler explosion and is ,an engine way too rich and a sources of air too, landing there, cracks in exhaust (2 failures) its only a symptom of a gross rich engine or gross misfiring, with unburned fuel landing there. the CAT will be red hot. still have a CAT?

---

if car was a 1996,(1998 in canada)
you;'d have DTC errors P030x, misfire errors.
because it IS.
wish i knew all conditions it did so, hot,cold both? engine?
or only idling hot.
or all the time.?
the when , really helps , in diagnosing all engines, for misfire.
most are spark caused. (not all) just most.

one easy (just random guess) way?
is too high fuel pressure.
34psi is normal but if 60psi, it will misfire all the time.. and suck fuel like mad. (this is not spark related its , fuel caused)

[Zackman]

Dear Fixkick:
Thank very much for your detailed reply.
1. Absolutely no misfiring whosoever!
2. I get code 12; no problem with the code.
3. I put a set of Bosch wires. I cleaned the tips (no oil; but somewhat black); still a bit rough soundinfg!

Cheers,
Zackman

[fixkick]

all rough idles, are misfire.
when the engine is too rich (example) that causes too rich misfiring, and is like 99% of all misfires on G16s this.
if you watch the engine it shacks and you hear the uneven beat ,that is misfiring,,, on all engines.
that black is rich misfire, normal is (cream, white, super light gray, but never see carbon of any kind there.) or is MISFIing
ever run a chain saw?, that uneven idle is misfire.
this ecu is brick stupid, it sees only, things that fell off, or shorted. (code 12 means , nothing fell off EFI inputs) that is it .... yes, dumb is the word on this ECU
and is same ECU used on all sidekicks,/tracker/sunrunners) same for same transmission. 56Bxx it is...
not like the 1400 errors my new jeep can throw.
code 12, does that mean you can drive car and it flashes 12s driving, (this is important because not all problems are static, problems can be intermittent or LOAD and vibration effected)

what do we know, ?
"thing to improve the performance" so what does that mean?
you never ran a 80HP G16a before?, or you have and this new engine is weak. ?
you say its rough, that means when cold /hot or both,?
if its rough hot, that is called misfire, for sure.
rough does mean misfire. and if cat is old and dead, you even smell it, if cat is new the cat over heats on all cars made, (gas)

if engine is weak, (say so) and if its rough then it is misfiring, we can work that, my page has very long misfiring section.
misfires has vast causes, over 50,,but if reduce that by saying engine is GOOD. (as it seems) and vacuum gage shows no bouncing then
the new (used )engine is good.
so next is spark then EFI.
lets do a list. first,
engine is ok, 150psi. cam belt seems not slipped,. it will do 170psi warm or hot, engine.
so if spark wires and plugs good, and gap at 0.028" never ever at .045" as sold in all new boxes.....
then we check spark timing,
is hot rpm always at 800 rpm??????????
with that working
we insert the timing freeze jumper and check spark timing, (normally it bounces like mad, all EFI does that) so needs the FREEZE jumper set.
ok lets say you did that and its at spec.
that leaves EFI issues.
what is next, my jeep books are 10x better on this....
my jeep books show 12 things even modern cars (EFI BRAINS) are blind to,
#1 on that list (and true here)
is fuel pressure, the ECU can not inject fuel properly unless it's correct.
but costs $20 to buy the tool.
if say the FPR fails as all do about now. the reg can stick closed, and pressure shoots from like 34psi to 55psi, and guess what, ECU IS FLUMMOXED.
on a hot engine so can a bad 02 sensor. cause rich misfire
so can a leaking injector
so can a crack near the 02 sensor, exhaust cracks are nOT allowed, there. ever. air has 20 % oxygen, and 20% slams the 02 lean, and EFI goes max rich.
ECT does not read 300-OHMS hot, get engine hot, key off, ECT unpugged, it measure 300 ohms if not, near there (ball park) this is a BINGO HARD FAIL.
the ECU has no idea at all what reality is., it trusts the sensors, so a BIASed sensor is UNSEEN.
Unseen means it has no way at all to know, IT'S WRONG.(it can only detect DEAD sensors)
IAT reads correctly? . using my IAT,/ECT page (chart, it uses the same ohms rules)
if all is ok, with ECU inputs, then the ECU is bad.

the ECU injects on inputs,.
and if those are correct and injection rates are wrong, (excessive)then the ECU is bad. (fuel pressure above at spec and 1st)
one way for this to happen is a short, injector driver transistor. (the other wire fires, but timed wrong)
the other way is the ECU has bad CAP.'S.
with bad caps the ECU keeps rebooting over and over, like a drummer boy beating his drum, (all caps 89 to 95 all fail 1 time. are yours original)?
called Rubicon death?
this cause the ECU to go nuts. and injects wrongly, and it's too stupid to warn you. (like today's cars will do)

your ECU is not in limphome mode 12s, that too is rich misfire if not 12s.
your eCU is not in backup mode, it flashes 12. so , not this..
both modes will caused misfire and both are rich and gross retarded sparking and loss of power. (limp is the key word here).

recap.
engine tests good
spark good. timed to spec, gapped to spec.
no exhaust leak near 02. (cracks or gaskets bad there, not allowed )
fuel pressure at spec. and the injector leak down test passes ! and the FPR tests pass. (pressure on 8v holds steady.) unlike the G16b , why more complex that.
ECU inputs tested. (all) includes map tests. see my MAP page, there is a page for every sensor.
ecu bad.? cap leaking, did you look first, this is day 1 check after loose crank bolt, pulley bolt. not at 94ft/lbs.


that is it! for TBI tests, its only got 1 injector so is more easy, and no funky MAF.

---

forgot to say the #3 check
engine reaches and holds 180F or more water temp.
it must. holding matters, this year engine, you never told me the year of used engine,
the 1994 car has 2 intake manifold. G16a
you can not use the wrong thermostat seals or the water temps will HUNT like made, endlessly.
and ECU goes nuts with it.
type frigid in my search box
http://www.fixkick.com/Cooling-engine/Fr...r-cab.html

what thermostat housing in hand, if lip is 4mm on manifold pit edge this is NEW style.
and must have a rubber ring seal, , MUST.

or it will run rich and misfire and will lose power. and performance,