Question about Saab 9 5

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Car has a tendecy to surge rpm when at idle or first put into gear seems to stop when engine becomes hot

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Quite likely to be idle bypass valve. On older Saabs, this was located in two hoses near the throttle body, but now they are usually integral to the throttle body. A quick and low risk way is to remove the bypass valve (unplug the electrical connector first) and clean it and the seating in the throttle body. Try putting the connector back on, turn ignition on, before replacing the valve in the body. It should move smoothly, if it does, then hopefully, you have a cure, if not, try another clean or buy a replacement. If it does move smoothly it wasn't the idle bypass valve and more diagnosis will be required.

Posted on Jul 29, 2009

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2000 Suzuki Esteem 1.8L.. I went to start my motor & turned it off right before started. I heard some kind of backfire. Then I started it and it's been idling high, the surging. Please help!!


scan it yet, a FULL OBD2 scan? why not?if not.
now is the time...


the 1.8L J18 engine, same as the older Sidekick sports used.
same engine , know it I do.
its the precursor to the J20, (j18 is under-stroked, j20 with many of the same parts. inside)
the back fire means explosion sound to rear end of tail pipe?
yes, that is rich raw fuel in the muffler. plus Air.
if there are exhaust cracks and then engine goes rich this can happen( a double failure)
if how ever BACK means, back to the Air cleaner, then that be different reasons, (timing)


engine now starts.?>
engine runs.? has full power, car drives ok.?
JUST?
SURGE,. you never said.

does engine get hot? 180F or more and holds (y/n)
ever get a full tuneup this decade,
most dont so i tell you, bad spark causes, misfire and raw fuel is wasted to the exhaust and sure can go boom.

surging usually means the ISC can not control idle
so it hunts, (a suzuki software engine on all 90s engines)
PCM errors, inside it. (dangerous too)
a modern car, if idle goes too high the ecu commands the ISC closed
and holds it there solid, (safe way , no hunting allowed now)]
so if this car surges, it's , lean engine.

some think flooding is surging.
and this is usually below 800 rpm,
almost stalls, then corrects, seems like a surge.

next time post rpm range of surge.?????

do not drive a surging engine, do not be like Toyota drivers. (over 800 rpm hot)

surge from 400 -800 rpm is class 1 surge.
surge from 800 to say 2000 RPM is class2, and very dangerous to some folks, (key off, get car fixed, tow it)

The ECU controls idle speeds. (hard coded servo controls)

Mar 18, 2016 | Suzuki Cars & Trucks

2 Answers

What is causing the fast Idle and slowing down


well gee, there are 50 reasons.
did you scan the PCM yet, if not ,why not?
when the idle surges, that means.
NO RPM ranges stated, if super low rpm check EGR.

1: engine lean and ISC dead, or cant handle the huge engine power drop..The PCM can even make this worse!, buy hunting the ISC to find spec, idle and failing... to...
2: or any of 50 other things causing huge engine power drop and PCM can't maintain idle controls.
super lean burn.(bogging)
super rich burn, misfire for 50 reasons.

i cant hear your engine,nor feel it, or see it shake from gross misfiring.
no can i drive it and see/feel power loss,
can I?
asking net bunny's this (blind as bats)
is "OVER THE TOP" no?
so here , ill toss the dice for you
and guess gross misfiring.
ever get a tuneup this decade, if not bingo , no?

and the others...

http://jeepdied.com/Misfire101.html

link even has the 50 cause list, to show the futility of guessing!
we do 1 to 10 tests. and find it.
for sure.

as you can see EFI systems are complex.
gue$$ is not only expensive but can net you 2 problems easy.

Feb 05, 2016 | 2002 Jeep Grand Cherokee

2 Answers

While driving my jeep seems to be shifting gears the rpms rev up and then goes back down almost as if surging I changed speed sensor as a guess so far but did not work?


old 1995
we need vastly more symptoms then that,sorry
if the engine surges, that is first. (surges in 1 gear)
but if a transmission down shifts that is normal, rpm rises
(after all its a lower gear) (higher numeric ratio)
find any machanic in town
ask him test drive it.!
10 min.later he wilt tell you
its trans issues.
or its engine, super easy this is driving.

seems you can not, and learning is 1hour in car class..or 10x that lacking facts of drive train functions.


stop guessing. why spend cash on a useless sensor now.
spend cash on $1 shop diagnosis and WIN.
i promise !

or get it scanned.
and post all those DTC errors. P0700? and more.

Jan 24, 2016 | 1995 Jeep Grand Cherokee

1 Answer

When I start my odyssey it starts surging. I found a small rubber hose on the right side of the engine, but don't know where the other end of the hose goes....Help


WHAT COUNTY???????????????????????????????????
hot engine, cold or both?/// a key question
WHAT ENGINE: ( usa list , ONLY)
2.2 L F22B I4
2.2 L F22B6 I4
2.3 L F23A I4 2.3 L F23A7 I4
the fsm covers this. hose thing.... all hose can be followed,
unless its axle vents on 4wd cars. (they go no where, special)
is surging the only symtom.?
no engine stalls.?
lack of power in any gear or hills.
no misfiring?
no flooding.?
starts easy/?

ok what is surge, that it really is idle controls bad or out of comtrol
1: idle controls bad. (isc dead?)
2: or engine is running way too lean, and ISC cant keep a grip on idle.

easy huh?
and #3 misfiring so bad the idle controls fail.
are all fuses good?
is the CEL lamp glowing , then goes out running engine.
no , the scan it. or do the flash DTC codes trick.

a good tech ,first finds out if the engine holds closed loop status
hot. at idle, if not, he fixes that first.
as he/she knows that idle is the last thing to work right, in EFI.

one other way to get surge is air leaks (aka. vacuum leaks)
if the engine (unsaid option) is MAP based, it will race fast
with any vacuum leak, and it dont take much of a leak
to make the ISC idle controller go nuts.

so repost , hot/cold both questions
and actual RPM numbers. we need numbers
is the dash Tachometer missing. ????
and what engines in car.

all lean engines surge.
all ISC systems can surge if out of control , not all do this. just 1/2
if the ISC surges, it means its trying hard to gain back control.
this is called a software servo loop.
The ECU is programmed to hold rpm near say 800 RPM hot.
and is very digressive in that role.
I have a 91 car that will surge, with any vacuum leaks.
(by design) depends on which engine.

Feb 15, 2014 | 1995 Honda Odyssey

1 Answer

97 toyota surges at an idle


(which engine. ?????)_
as always check all fuses. and scan the ECU for DTCs. first.
there is no need to fix OBD2 cars like 1980 cars (hard rows to hoe)
it can be 2 problems this......
lets fix the easy one first. idle. (and hope for moving issues to fix for free) it idle car is parked, so is 100% safe tests. (not moving)

so it surges at idle.
questions.?
1: hot or cold or both.?
2: low extreme RPM and high at idle.

400 to 800 RPM? surge.
1000 to 2000. what? numbers tell the tale.

first off, idle is the last thing to work right on any engine.

there are many ways to find what is wrong.
fix idle surge way.
i make sure that the engine holds closed LOOP status.
hot idle, if not , i fix that first.
keep in mind if not in closes loop and lean
all lean engine surge and guess what the ISC will add to the surge
because idle is way too slow, so the ECU open the ISC wider
and wider and its still too slow, so the ECU resets the ISC
this cause a worst hunt (surge)
the ECU adjust spark time and the ISC to get 800 rpm. (spec. look up yours)
so say , i see closed loop failed, OBD2 scan page 1
i look at the O2 sensor an its stuck lean.
if stuck lean and it really is (o2 bad?) then its lean and it will surge
.
examples.
1: i find 02 sensor bad, (only effects idle and light steady cruise)
2: i find fuel pressure at 15PSI , hopeless low .
3: i find all injectors clogged. and lean.
4: with MAF EFI, ( i find maf reading too low, (dirty) causing lean.
5: if MAP car, i find the MAP stuck hard high vacuum causing lean.
not knowing what engine you have or the idle hot surge range,
i can not go farther.

the driving bog tells me,
1: scan the ecu ,get DTCs; do that first.
2: clean MAF if car has one, ask how..
3: check fuel pressure.


my guess is engine is lean. and starving for fuel all the time.
cept WOT.

MAF cars starve for fuel if there are any vacuum leaks.
MAP cars do opposite, they race fast with 100% full power.
MAF is air density EFI
MAP is speed density EFI.
apples and oranges diffr. so what engine.


Jan 07, 2014 | 1997 Toyota Tacoma

1 Answer

Throttle surge at idol


surge, great post, what engine displacement.
open hood (my answers are USA only) look up, see big white
sticker that is the engine vacuum and type engine sticker)
surge hot or cold? engine.
if it surges hot, that means :
1: ISC system out of control , it job is to stop surge and 5 more things.
2: the engine is way lean and cause ISC to loose control

just 2 reasons, and can be 50 things. wrong.
is the CEL lamp out running> if not, pull the DTC codes and post them. (all)
as a mech ,we find out which it is.
(i make sure my engine can hold closed loop at idle , if not and lean it will surge. (may)
we make sure the ISC works ok (not sticking, clean it)
and then test to see , that if by my forcing it closed, by hand (ask)
i can get way below 800 RPM. most do 500 but 600 is ok.
if rpm stays above 800 closed, that means you have huge
vacuum leak or TV blackage (too thight throttle cable?)

finding vacuum leaks can be horrific, task .
there are many tricks (and tests) to do this, ask.

see that logic above, If I the mech, can not drop rpm below 800
by hand, then no ISC on earth can. not now or ever.
and proves the induction has huge air leaks
or some dolt set the spark timing 20 degrees advanced.
see it.
so as always , a tuneup is first, then as always , i always check timing,and for proper advance rates.
advances engines at idle race way too fast and the iSC will just go NUTS.

ISC = Idle speed controller , that valve that has wires.
the IAC is a thermal device and no wires and it too can stick open
when the IAC sticks open the ISC goes , yes, nuts,
nuts can be surge (ECU is hunting it)
or just racing way too fast hot, say 1500 rpm.
a slow RPm can be a stuck open EGR (50k service point)
lean will cause too low.
too rich , misfires and too low
the ISC is the last thing to work right, all else must be good.

what does your CEL lamp do?

PS: most cars, if the ECU/PCM enters Limphome, it cuts all idle controls. again, the CEL lamp. glowing while running.../????

Nov 28, 2013 | 1994 Honda Civic Del Sol

1 Answer

Increase then decrease idle when engine is cold especially


cold engine idle surge. (problem)
RPM range of surge not stated
300-700 or 800 to 1500? (range is critical to diagnosis)

bad fuel
running summer fuel in winter (running old fuel?)
needs a tune up bad, see the list in the operator guide.
idle speed controller,sticking or EGR valve same. (clean them)
location not stated, so cant guess about local air temps.?
no other symptoms, lack of engine power? etc?
was it ok last week, or better, when was the last time it was OK?
1week, 1year?
surge , causes, on a tuned engine might be:
1: too lean. so lean the ISC can not control idle. rpm low, stalling
2: too rich, flooding, stalling, spark plugs foul (look at them)
3: weak compression in 1 or more cylinders.
4: bad spark.
5: air leaks, in the plenum causing , ISC to lose control.
why high RPM?

especially?
well that means it fails hot too.
and there is a simple tests. for hot surge.
is engine fully hot? 180F and holds solid there?
say rpm is about 800
and you turn on head lights, heater fan and (not AC) and defrost.
the RPM must hold or the ISC is failing.
ISC -= idle speed controls. (all EFI has this function)

Oct 28, 2013 | 1996 Honda Prelude

1 Answer

2001 Toyota Celica GT RPM surging at Idle


Certainly sounds like the o2 sensors have become contaminated and are not acting as fast as they used to , or are supposed to.

Apr 24, 2009 | 2001 Toyota Celica

3 Answers

Low rpm's in idle when heating/cooling system is on & surges.


Check your EGR or your Idle control Valve. This can cause a problem with your irratic idling

Apr 17, 2009 | 1995 Ford Explorer

1 Answer

Eng. rpm not dropping when clutching & at idle, rpms go up & down


Here are a couple things to try. The idle surge is a common problem. Ford makes an adjustable plate like the one below. It allows come control over your idle. I made one and it eliminated most of the surging. I think the Ford part is about $30. Can't seem to find the ford part number though. Search online.

http://k-mansparts.com/items/performance/ford-mustang-iac-adjustable-idle-spacer-kit-50-46-f2pz9f939a-detail.htm

Try www.fordfuelinjection.com or other ford sites. Lots of great information.
My 89 seems to roar loud when cold when coming back down to idle and I am sure its the fan clutch. I have also heard the water temp sensor can cause idle problems because the EEC does not know what state the engine is in. (hot/cold, etc)
Hope this helps. I do recommend the adjustable plate though.

Feb 03, 2009 | 1987 Ford F 250

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