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Comperssion Check
Hey guys I did a compression test on all cylinders, and here are my results. 91 kick TBI 1.6 8v

1. 150
2. 165
3. 160
4. 165
Did the wet test to and nothing changed, what do u think?
that baby is ready for cross country runs.
that's a nice 8v you have. nice rings too.
(04-19-2014, 08:26 AM)fixkick Wrote: that baby is ready for cross country runs.
that's a nice 8v you have. nice rings too.

I read on the suzuki forums that it should be pulling 170.
Anyway.....you are the first person that I have talked to that gave me a full answer ty for that. Maybe you could help me with some other issues Im having.
I have been dealing with idle issues and have replaced most parts like the TPS, IAC, EGR, MAP, Fuel Pump and regulator, Timing Belt, due to the age of vechicle. The idle seems a lil wierd it hunts and I cant seem to get it right, neither can the dealers. When I come to a stop the car almost dies. Just today i set the rpms back to 800 as it was running at 1000-1200 and timed it 8 TDC, this changes all the time, cant keep it straight.Confused the other problem I am having is I sometimes smell antifreeze thru the vents when using the heater. and i lose coolant in the radiator, I cant find any leaks and it doesnt overheat. Have replaced the radiator and thermostat 180 deg.
on a hot or warm engine
the factory spec is.
My 91 8 valve, pulls 155 psi. (dead cold at 72F) Suzuki FSM stated, minimum spec for hot coolant is 170 PSI
any cheap gauge can be off 5psi easy.
also, Altitude drops compression.
cold is less, because the cylinders are not fully round yet. (factory bores, are drilled, hot for best seal running - 2nd reason is the head bolts the most tight hot, and cylinder were bored with dummy head plate bolted on , so that hot cylinder deformation is zero, hot.)

1: heater core is leaking, making that sweet AF smell. (we have page for that)
2: idle regulation is complex.
are you using only the idle bleed screw to adjust the idle?
it is idling at 1000 and dies?
the #1 cause of any stall on 8v is EGR sticking open, the 8v ECU opens the electric IAC (isc) and prevents any stall, only the EGR can prevent the ISC (aND ECU SOFTWARE) from
preventing the stall.
here is a short hit list. Hot stall.s
A: EGR, stuck open..
B: ISC dirty, yours is new, so the TPS was set wrong. the idle switch must be closed at idle.
C: any illegal air leak.
D: the dash pot must not be holding the throttle open at idle. (5-30after any cold start)
E: CEL not glowing, running, (limp home mode there are no idle controls)

this changes all the time, cant keep it straight (idle or spark timing?)


low idle (EGR is #1 cause) below is no order.

we can fix all probs. by simple tests.

the EGR must snap shut. easy. or its dirty.
The ISC must be clean. (yours is)
There must not be any induction air leaks, putting the ISC out of range (duty cycle all wrong)
air leaks never cause stalling only racing RPM with 100% full horse power.

that stalling is EGR or flooding.(gross misfire)

1000 feet 170psi times .97 is 165 PSI. (just a tiny bit of altitude , drops compression) per table below. FSM table.

[Image: altitude-x.jpg]
1. Hmmm if its the heater core leaking that is gonna suk, I have original equipment which still works. which means I will have to convert over to 134, cause I cant find anybody in my area that will charge my system.

2. Yes bleed screw. When my idle jumps up to 1000 and stays for the duration of driving it dosent die. (A random thing) Next time I drive the car idle is fine 800rpm and almost dies when stopping. My idle changes all the time.
EGR is about 3 yrs old and clean.
So im thinking its the TPS, it is new aswell but hard to find someone in this area that knows what they are doing.
Had the shop test for any vacuum leaks, none were found.
The dash pot has not been replaced but I tested that myself, and the diaphragm moves freely.
The cell light comes on at key turn and goes out when started.
Just yesterday I set the idle to 800 again! Jumped the C&D terminal and checked the timing, was off by a hair My question on this answer why do I have to adjust idle and timing so much?
The other thing that sticks in my mind is maybe its the ECU. I have not replaced any components in there or even looked at it.
Im a backyard female mechanic doing pretty good so far lol.
just he heater core, is leaking, check near passengers toes for signs of leakage. or just the hose as it just passes through the fire wall, almost no hose this old runs at 12psi, not that old.
see core here?
rule 1, never twist this hose or it breaks off the core nipples, use cutting tools to remove hoses, then slide new hose on. zero damage.

great questions, all !
the eCu controls idle, so if you change the bleed screw, and idle changes, that means the ECU lost control of IDLE speed, the ecu sets idle at all times. no you or me, ever.
how are you setting idle , via what device, there are 3 ways, to change idle speed. only one is correct and only one is for dutycycle not idle.
My question on this answer why do I have to adjust idle and timing so much?
first off , spark timing requires, 800 rpm , hot, accessories off, and idle is not settable.
let me explain,
there are 3 throttle cables. to be set wrong, they must all 3 be set to slack. or idle will fail, due to them pulling on the throttle illegally.
throttle cable, 3speed kick down cable. and the cruise cable, my car has only 1, its 5speed.
the idle switch must be closed, or idle controls are dead, and this failure you will notice that the bleed screw changes idle speed, that is because the ISC is dead.
There are no mech. that know these early 91 cars. 89/90 even worse. they dont , nor how to adjust them. (that is because on newer cars all these settings are Fixed)
you start the car, did the dash pot, retract 100% you will see an air gap between that DP rod and throttle cam. this means its retracted and not messing up idle, at all, (not touching)
now with the car hot idle, pin the cool ISC air line 100% RPM must fall to like 400rpm or near stall.
if it dont do that , that means there are air leaks (vacuum leaks) and is why the ISC has lost control.
this screw with white paint must never be fiddled or changes, or the ISC will FAIL. (the white paint is the warning, dont touch me)

the ISC can not correct 2 gross errors.
1: hug air leaks that when it closes RPM is still over 800 RPM.
2: EGR stuck open (or gross engine timing retardation) RPM is way too low , such that opening the ISC 100% the ECU can not attain 800RPm
this is the limits to the ISC command authority. it can not correct for gross errors.

the TPS pins A to D are here
see test 4

on car test. do this at any time hot. (hot engine)

the car, idle test , is to turn on headlights, and blower fan and defrost if you have it, does IDLE drop, low? bingo no idle controls at all.

timing off
timing off a hair is no big deal. you will never get it perfect.
if it bounces like crazy ( normal not in freeze mode) but if it bounces in freeze mode, that too is a clue that the idle switch is not closed.
the setting of timing, its mandatory that the idle switch must be closed,
why? because the ECU things your are driving, and when it thinks that , it suspends idle.
The ecu believes the switch 100 % all the time.

just ECU caps need checking for leaks (acid spills or signs of that)

the FSM page is here.
for the cal.

the correct feeler gauge for 1991 is 0.016" threshold and the GO gauge is 0.012" most go to zero volts.
my tps page as a table listing all engines all feelers used.
it is fairly critical.
if set wrong, no idle.
if set to open late this causes TIP-in hesitation. (ISC fights your right foot , in this case, very bad that act)
the FSM page is not option, one can not guess it to work right. it must be set.

Idle controls are what is called a SERVO.
the ECU and the ISC from a SERVO loop
when active , the ECU holds idle at 800 RPm (in a closed loop style) even with alternator sucking 50amps. , the Power steering moved.
the bleed screws set the center point of this servo, to 50%
this allows the ISC to add or subtract air, 50%, this adjustment centers the ISC on a hot , no load engine.
on a working kick the bleed screw never changes idle. that is unless , you dont exceed the range of the ISC.
as air gets colder it has more oxygen, and the ECU adds fuel and the engine wants to race. the ISC corrects that too.
it also corrects for engine wear and lost compression.
it also adds 200 rpm for A/C on.

with the ISC dead, the engine rpm will vary by all the above.
I only have one throttle cable. Mine is a 5 speed to.
I adjust the idle by turning the bleed screw on the throttle body. No one has touched the throttle stop screw.
Let me get this straight.....if I adjusted the idle bleed screw on the throttle body the ECU lost control? How do I get the ECU back on track, would I have to replace this? If I replace the ECU what happens to all the adjustments I have made prior? Will that effect the new ECU and will it lose control again?
the ECU controls idle speed HOT , it's an EPA law that. (unless malfunctioning)
tests must be done, before replacing parts.
the ecu is hard coded for 800 RPM , every one,, not just yours,.
the first step, is the tps idle switch it must be closed.
if not, all this is a wasted effort, if the switch is not closed, idle will vary all over the place because , idle controls are now dead.

you proved its dead, now only why matter.
TPS idle switch tops that list. i bet it was never set when replaced, i bet the mech, don't even know it must be done,
on newer cars you set this TP angle at 0.5v (1.8 L and bigger) (this method got rid of the switch) hoorah.
on even newer cars, the ECU auto learns this step. Cheers to that.

idle controls are active only at idle, never driving, the ECU knows you desire idle , only by lifting your right foot and the idle switch closes, and the idle servo system , activates.
yours is not.
it's that simple. (there are other causes but this one is the most primary reason)

other causes"?
EGR stuck open
gross retarded cam
gross retarded spark timing.
or a dead cylinder.
or 80psi compression, (a near dead engine)
ECU in limphome (CEL on full time)

on all engines, idle controls are the LAST to work right.
when tuning a custom ECU, it's the LAST step. in a long process.

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