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Warmed up, idling too fast
06-06-2017, 10:43 PM
Post: #1
Warmed up, idling too fast
Howdy, long time no see. Hope all are well.

Am at 184K miles, about, original engine.

I seem to have developed the somewhat common fast idle issue…where the warmer the engine gets (starting from cold), the faster it idles?

If I let it continue creeping up, it goes beyond 3300 rpm. Starts fine cold, idles up to the usual 1600-1800…comes down a little, then when you'd think it would begin to go back down to 800-900, starts creeping up the more the engine warms.

I have the 8 valve engine, 1992 4wd 5 speed LSI. Has the original thermostat on this car I think, still. That a potential cause of this? No obvious vacuum leaks found yet, though reading through some posts here indicates likely cause.

This is a warm-up idle problem…hotter engine gets, faster it idles.

Old news: my DIY rebuilt trans with the lovely bad-ebay-seller-maybe-sent-me-used-bearing noise now has 1,000 miles on it since, still noisy, but still working-- though I have what sounds like either a U-joint clunk on letting the clutch out sometimes (in the back), or (gosh forbid) the driveshaft nuts loosened…still need to check.

Second gear still grinding on the shift until warmed up all the way. (only in motion, stopped is perfect). Not sure if due to gunky synchro, or just that oil I used is not loved by 2nd gear synchro sliding parts.

Thanks for any suggestions on the idle.
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06-07-2017, 09:43 AM
Post: #2
RE: Warmed up, idling too fast
(06-06-2017 10:43 PM)GeoHacker Wrote:  Has the original thermostat on this car I think, still. That a potential cause of this? No obvious vacuum leaks found yet, though reading through some posts here indicates likely cause.

Update, just took another drive. Started, went to usual 1800. Idle never went down below 1600. Went a mile or two down the road. Idle went up to 2200…cold needle on temp gauge, at C mark.

I stopped at an intersection…soon as temp gauge came up (thermostat opened?) car changed to surging between 1500 and 2000…would go up to 2000, come back down to 1500…go right back up again (every 2-4 seconds) temp gauge too past the middle, too fast.

While at the light initially, the temp gauge was at bottom C…by time across intersection, surging started, gauge went almost to half way instantly…that is not normal for my car for the gauge to go up that far that fast.

Checking for a leak soon as cools back down. Sure hope it isn't that one hose I never could get to to replace, the one on the passenger side of the engine under all the works which kind of seems like you have to take the engine out to get to the clamp up front near the water pump. Sad

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06-07-2017, 09:57 PM (This post was last modified: 06-07-2017 10:41 PM by fixkick.)
Post: #3
RE: Warmed up, idling too fast
lots of probem, idle , surge, 2nd gear, air in top of block air pocket causing temp sensor to go nuts, it can measure air temp so goes nuts on all cars same reason (or wire there is rusty)
the surge is first. this old suz has flaw in the software, illegal now, very much so, and surges when it can get idle to hard coded 800 RPM hot, its software bug. (my guess, bad programming then)
2nd gear (off topic, i think is your clutch cable is bad, and clutch drags. moving should be less 2nd gear balking. not more, do to less differential gear speeds)
so forget surge, its a side show, a casualty of primary cause. below.:....

the true failure in all cases, (not bad parts, science) is you HAVE AIR LEAKS, (AKA. vacuum leaks, ) IT FOR SURE IS>
if you at thin moment, block, all air leaks to the PLENUM (that large caviting below TB) that collection point below the Throttle body , all 8v stall , dead, hard stall, this is a fact.
so to is that all air leaks cause racing way too fast, idle speeds, hot. (unless its just tiny tiny leak that ISC corrects easy )

knowing just that fact on speed density EFI one can work the problem some are easy some are hard find,
the first thing to do is look at the dash pot, on rear of TB, see that rod on it, it has 1/8" gap there if not the DP is bad. (or its controls)
this takes 1min to see this. its super easy check DP is it, or not. DP is is off , hot running,
1: 1 to 3 throttle cables not set to spec 10mm slack, , the 3 are, throttle, TV, and cruise, you dont have TV so 2, cables, if cruise fitted
TV cable "passing gear cable" = on automatic trans only.
set the slack by the book now (need link to book?) and fix that now, if needed.
TV = throttle valve that brass butterfly plate in the TB. when you step on the gas you are really stepping on AIR. (EFI does the rest)

2: TV (it self)is blocked open for many reasons not #1 , gunk in the TV plate blocking it open, sucking massive AIR.
3: IAC leaks, the wax pellet is bad, or the hose feeding water to it, is dry and IAC goes nuts, just like the dash gauge is doing, omg, same air pocket?
The IAC closes 100% at 150F. but that takes water flow, in that hose, some are clogged in hose or the 4 points of enter and exit fittings.
4: ISC stuck open (umplug the wire to it, connector, rpm will go to 400rpm if not, the engine has vacuum leaks for sure. all connectors have locks do NOT FORCE any. they are not sold, suz connectors so, being careful is everything here.

the IAC is not easy to test, if hits hot, 170f shows on my IR thermal gun pointed to it. if not but is colder far colder that 180f thermostat reading
then the thermostat is bad, stuck open that water path the the ISC is bad, clogged. (its not flowing only why is question)
the IAC can be air path blocked, it has an air port, that can be blocked proving that it is stuck open. (temp checks are first, it must go over 150f to work right) I have photos in my TB slide show , see that?

5:vacuum hoses leaking. (all ways any way , its bad)
that means the thing on the other lend of said hose must not leak air too. including that brake booster, we use hand vacuum gauge tester (pump)
we do hose inspections and vacuum leak down test with that cheap tool. harbor fright has a nice one,
the PCV sucks fumes and is orifice limited and is not leaking air. normally. unless the hose is cracked, back to hoses....
The other devices, must not suck air, map, Dashpot,FPR,booster,broken VSV valves, there hoses, EGR hoses bad. but parked, at idle , EGR is off line, but the hoses and the valve must not suck air , ever, here. , one can just pinch hoses to find vacuum leaks, its super easy until booster hose is found , its huge and think and refuses to pinch so, we use a cork, wine bottle cork the bugger, see , now? see idle drop or not? dont drive now, with cork in place.
A golf TEE is a great tool to block small hose ends. to prove leaks or not, lacking hand vacuum test pump tools....mightyVac, or HF tool cheaper.

6:other leaks, intake gaskets. (saw EGR main valve cracked in half sucking massive air, seen its gasket missing, sucking air)
nature hates a vacuum (on earth only)

my slide show and idle failure pages cover this horror.
ignore all 16v pages, its not the same animal.

get a cooling system flush and all hoses small checked for full flow, end to end.
no air pockets on top of engine
thermostat not 10 years old (hopeless to fault this)
wrong thermostat, 160f (hopeless to a fault this)

SEE ME bench marking it here, in pan of water and in my FREEZER?.?
the gaps were measured with number drills set 1 to 60) using there shanks. this photo exists no where else its my work.

see this horsed up map I made?

see all those paths to leak Air, lots no?
The TV is 99.9% closed, at idle, it must be, and idle air is only IAC+ISC+bleed air when working correctly.
The IAC is closed HOT, if not its failing, ISC is the only air allowed except the bleed screw.
the bleed screw is ISC dutycycle calibration, per book.

the most hard leak ever found or seen in 10 years
was the poor guy running water , not 50% antifreeze
that it allowed the TB to ICE UP.
this cause a "where no man can go or see, crack inside and behind the IAC guts" nothing less than a small horror.
this was found by ,engine ran great with hand on top of TB air horn blocking all air flow to TB and it it ran perfectly, and all gaskets were perfect.(all 3)
yes, horrors do happen.

1: someone played with the never touch screw the idle stop TV screw. (bad to the bone this)
2: someone unscrewed the idle bleed screw, fully. its not idle speed at all its duty cycle setting, ECU sets idle speed, this screw puts the ISC in the center of its command authority (1/2 way point)
3: the TB top horn comes off and has a gasket that fails and lets the Bleed suck air <ILLEGALLY) see 2 holes at 2pm below>?
ive seen the gasket go rock hard, crack and suck in and go byebye here, and sucks air like mad, that suck path is straight shot to the plenum too.

see this photo on my idle fails pages
see all those hints?
see that IAC suck port, I use clay here to block it and see if ISA is sucking air hot. a difficult check but is proof.

[Image: cold-air-n2bw.jpg]
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06-07-2017, 10:46 PM
Post: #4
RE: Warmed up, idling too fast
water temp wrong, is a first order problem.
fix first.
if you had a scan tool (real) it shows ECT doing same funny wild dance?
that means AIR pocket, for sure. (both sensors can not read air temps at all , they work only SUBMERGED)
if not that means the Dash temp gauge sensor is bad, or its wire is loose rusty or like seen many times the 1 wire gauge sensors pin is damaged and loose and flops about. BAD.

hot engine 180F
key off
take off ECT sensor, connector DMM ohms meter to the 2 sensors pins , 300 ohms = 180f per my ECT chart.
and auto ranging meter shows.

K in the LCD window.
and 0.3K = 300 ohms so show 0.3 on dial,, and the K mark tell you its x1000 range, .3 x 1000 = 300.
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06-07-2017, 11:21 PM
Post: #5
RE: Warmed up, idling too fast
2nd gear (balks or grinds)
my guess wrong gear oil used !
my old list

the tranny designer , used GL4 for those syncro's ( non trivial at all)
nothing else and for sure not synthetic oil. and not GL5 axle oil. (hypoid gear lube GL5) I do have a bottle of Napa GL (marked GL3/4/5 and it works great and do not know why, magic>?)

if sure the clutch is not dragging, parked going to reverse tells you if it is or not, reverse is non syncro gear and loves to grind first. does it?
the pressure plate can do odd things at high rpm, (cracks in it do that)

when you go to an auto store.

they mostly do not sell any synchro-mesh lube oil at all in stores, GL4 gear lube, due to , nobody today shifts.
when i get my car inspected (state law) THE GUY THERE CAN'T SHIFT A STICK (its a Brave new world, no?) (he's tasked to test my brakes by law, sad to watch that)

do not look at the MT rating on any gear lub bottle, that is for 1950 school bus with a crash box. or like my dump truck had in 1965.... 15 gears forward not one synrco.
the bottle needs to say synchromesh some where, or its no good.

if you look at that brass syncro ring it has grooves, those are TUNED for GL4 and GL4 only,

if you aks that store fibbers, (ignorant) sellers, with advice on syn lube, guess what? those groves are now useless. it slips now like mad and grinds (no matter when or what temp)
its not rocket science but is tricky this.
do not use the wrong GL.

finding real GL4 is one of the most hard things to do, in all 6 stores in my town, are not one bottle of GL4. sold if you ask the clerk some pretend to know what to do, do not LISTEN)
and the guy behind the counter never shifted a car ever in his life nor ever repair a box., nor ever learned how to make syncro happy.
He even gets a SPIFF for up-selling you that crap, synthetic lube. (conflicted to the max )
His boss tells him if not sure, UPSELL. ching ching....

my guess too #2 is that the rear bearing on the counter shaft is jumping about, did not you have bad spline there? loose? I forget.
I've told others here, I made one good box from 3 used boxes. (its not easy at all )
finding donor boxes is near impossible now.... (Suzuki does have some parts, but takes month to get if at all)
if the bearings looked new in a box and did not have funny (or worse non) markings on them then they are probably ok,
I found mine begging on CRAIGS list for months.

for sure I dont just slam in parts, that took 10 long hours labor to pull 4wd tranny. 5out 5 in.= 10. omg 5 out again? now is 15 hours. then 20....

I look at those so called new bearings for marks and the box. (seller on ebay are like stars at night, come and go, and change at drop of hat)

if they are KOYO, they are good, if the box matches the online KOYO pages for back markings, and not counterfeit form CHINA, then they are good.
China send lots of JUNK here as real, and is fake, all top bearing makers web sites warn you of this. and show how to inspect packaging
or how to buy bearings from there OFFICIAL USA distributors and be 100% safe.
the top 10 bearing makers are known, TImken tops my list and KOYO.
the lube must match what is called yellow metal synchro rings, there are others used, like my jeep has matrial there looks like BRAKE PADS, yah... and runs very special 6speed MT lube.
but the 600 bearing factories in CHINA, are not. sorry. with no name or "some ting wong"
or this.
can you read this?

look here, can you say those words, this is what to avoid. (all working grease knuckled mechanics know what these horrors are, it's means do the job the 2nd time for free ! "called COME backs")
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06-07-2017, 11:23 PM
Post: #6
RE: Warmed up, idling too fast
in a shop they scan it first.
to see why water temps are wrong? so it seems looking at 20+ year old funky cluster gauge
oops it is wrong? stop do not pass go; do not collect $200, fix that first.
and if they are wrong,(temps) the EFI (and more) goes quite mad.
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06-08-2017, 11:53 PM
Post: #7
RE: Warmed up, idling too fast
As to finding the proper gear oil, from my experience Pennzoil Synchromesh is good for our gearboxes.
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06-09-2017, 12:15 AM
Post: #8
RE: Warmed up, idling too fast
it always works , never seen that fail, used many times.;
but many stores do not sell it, (lack of sales, so is kicked off shelf for selling , Classic car engine oil and such,)
its #1 on my list , posted above.
see it.?
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06-09-2017, 12:18 AM
Post: #9
RE: Warmed up, idling too fast
here ill click the link 2times
and land
as you can see they still make it,
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06-09-2017, 12:22 AM
Post: #10
RE: Warmed up, idling too fast
if the main shaft is the box , jogs. shifting will be unpredictable.
be that bearings bad or splines in side worn out.
Clutch drag of any kind and at any RPM (foot on pedal to floor) the top cause here is bad cable. the cables do not last 25 years nor make it past 150k miles in most cases and LOVE to stick inside.
worn synchro rings or wrong lube, making them fail. do not use synthetic oil here, it will fail. in 9./10 boxes.
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