Saab 9000 hesitation under load
Discussion
Hi
Having a small issue with my Saab...
Car is a Saab 9000 2.3 LPT Manual
When the car is under load ie accelerating, or maintaining a constant speed up a hill, at certain revs (seems random at what revs it happens), it will hesitate. Just for a split second and then the power comes back in. It is almost as if a small bit of dirt/water went through the fuel system, I guess. Idles ok but hunts a little bit, just not a steady xRPM.
This problem has not changed since I gave the car a full service, including new spark plugs, new oil, new fuel filter and a shot of redex.
Any thoughts anyone??? Vacuum leak?
About 6 months ago (7000 miles or so) I changed out the DI cassette (coil pack) for a brand new one so it shouldn't be that.
Help!
Having a small issue with my Saab...
Car is a Saab 9000 2.3 LPT Manual
When the car is under load ie accelerating, or maintaining a constant speed up a hill, at certain revs (seems random at what revs it happens), it will hesitate. Just for a split second and then the power comes back in. It is almost as if a small bit of dirt/water went through the fuel system, I guess. Idles ok but hunts a little bit, just not a steady xRPM.
This problem has not changed since I gave the car a full service, including new spark plugs, new oil, new fuel filter and a shot of redex.
Any thoughts anyone??? Vacuum leak?
About 6 months ago (7000 miles or so) I changed out the DI cassette (coil pack) for a brand new one so it shouldn't be that.
Help!
From all that you're written, it sounds like you have a 'tranient fueling' issue. This means that on transients, when you "tip-in' on the accelerator- like you have to when you change load to go up a hill or go faster- the Air fuel ratio is incorrect. It's unlike to be the incorrect grade of plug- as this kind of mis fire wouldn't just manifest itself only during transients, as you've indicated, but continually.
The mixture during transients is likely to be too rich or too lean. Out of the two there are more symptoms that can cause it to go lean.
Check the manfold pressure sensor, check for engine air leaks, ( even check the lambda sensors-[unlikely as this wouldn't just manifest itself during transients), check the intake manifold temperature sensor
The mixture during transients is likely to be too rich or too lean. Out of the two there are more symptoms that can cause it to go lean.
Check the manfold pressure sensor, check for engine air leaks, ( even check the lambda sensors-[unlikely as this wouldn't just manifest itself during transients), check the intake manifold temperature sensor
Edited by Marquis_Rex on Wednesday 7th July 18:38
Boosted LS1 said:
Mine does this to and I was suspecting the coil pack. A month or so when it did it it finally wouldn't start one day and I needed a fuel pump.
OK, this sounds interesting. I will see if I can get a new pump for it. To be honest, I could do with replacing it anyway as its one of the 3 common things to go on the 9000 and I have replaced the other 2 (belt and pulleys, and the DI cassette)NiceCupOfTea said:
Do you have the right spark plugs in it? NGK BCP7EV or whatever they are?
Plugs are new and the correct type so hopefully this is ruled out. Also, it was doing it before and after the service which included plug change.
What age is it? Is it Trionic or DI/APC? Worth checking for boost leaks - how does it idle?
Its a 1998 P reg so its T5 I believe. How do I check for boost leaks?? It idles ok but hunts very slightly. To the untrained ear, it will idle fine, but because I am now “looking” for problems, I can notice is bobble slightly.Plugs are new and the correct type so hopefully this is ruled out. Also, it was doing it before and after the service which included plug change.
What age is it? Is it Trionic or DI/APC? Worth checking for boost leaks - how does it idle?
Any idea on the importance of this??
Dr.Doofenshmirtz said:
MAP sensor?
Bar buying a new one for nearly £50, how can I check/test this, if poss??Marquis_Rex said:
From all that you're written, it sounds like you have a 'tranient fueling' issue. This means that on transients, when you "tip-in' on the accelerator- like you have to when you change load to go up a hill or go faster- the Air fuel ratio is incorrect. It's unlike to be the incorrect grade of plug- as this kind of mis fire wouldn't just manifest itself only during transients, as you've indicated, but continually.
The mixture during transients is likely to be too rich or too lean. Out of the two there are more symptoms that can cause it to go lean.
Check the manfold pressure sensor, check for engine air leaks, ( even check the lambda sensors-[unlikely as this wouldn't just manifest itself during transients), check the intake manifold temperature sensor
Sounds interesting. Forgive my ignorance, but what is the best way to check the manifold pressure sensor, air leaks, lambda and temp sensors without buying new ones? I have no access to OBD facilities.The mixture during transients is likely to be too rich or too lean. Out of the two there are more symptoms that can cause it to go lean.
Check the manfold pressure sensor, check for engine air leaks, ( even check the lambda sensors-[unlikely as this wouldn't just manifest itself during transients), check the intake manifold temperature sensor
MrMoonyMan said:
My money is on your DI cassette giving up the ghost.
Maybe time to start carrying a spare at least.
This was replaced with a brand new unit only 6/7000 miles ago (new years day 2010)Maybe time to start carrying a spare at least.
Thanks everyone for the ideas so far. Any further info would be great
'98 will be T5.
Boost leaks can be hard to track down - the only way is to look really closely at all the pipes - which can be a nightmare with some disappearing behind the bulkhead etc. I ended up replacing all the ones I could with silicone ones.
I had a problem with my c900 a couple of years ago, where when I accelerated I would suddenly completely lose power & kangaroo. Embarrassing and dangerous. Didn't think it was vacuum as idle was fine. Replaced coil, leads, plugs, rotor arm, cap, but no difference. Was on the verge of replacing the injectors when I had a closer look at the larger gauge piping on the APC valve. Turned out the pipe between wastegate and APC solenoid had a split. Under acceleration the engine/turbo moved back on its mounts and moved the pipe as the APC solenoid was bolted to the bulkhead - split opened up, vacuum leak!
Gaffer tape confirmed, new pipe solved.
Months of hassle, swearing, replacing parts, considering selling, etc. Just shows that vacuum probs can manifest in all sorts of ways...
I would order some new piping from partsforsaabs and replace all you can - see how it runs after that. Will only cost a few quid and will save future problems.
Boost leaks can be hard to track down - the only way is to look really closely at all the pipes - which can be a nightmare with some disappearing behind the bulkhead etc. I ended up replacing all the ones I could with silicone ones.
I had a problem with my c900 a couple of years ago, where when I accelerated I would suddenly completely lose power & kangaroo. Embarrassing and dangerous. Didn't think it was vacuum as idle was fine. Replaced coil, leads, plugs, rotor arm, cap, but no difference. Was on the verge of replacing the injectors when I had a closer look at the larger gauge piping on the APC valve. Turned out the pipe between wastegate and APC solenoid had a split. Under acceleration the engine/turbo moved back on its mounts and moved the pipe as the APC solenoid was bolted to the bulkhead - split opened up, vacuum leak!
Gaffer tape confirmed, new pipe solved.
Months of hassle, swearing, replacing parts, considering selling, etc. Just shows that vacuum probs can manifest in all sorts of ways...
I would order some new piping from partsforsaabs and replace all you can - see how it runs after that. Will only cost a few quid and will save future problems.
NiceCupOfTea said:
'98 will be T5.
Boost leaks can be hard to track down - the only way is to look really closely at all the pipes - which can be a nightmare with some disappearing behind the bulkhead etc. I ended up replacing all the ones I could with silicone ones.
I had a problem with my c900 a couple of years ago, where when I accelerated I would suddenly completely lose power & kangaroo. Embarrassing and dangerous. Didn't think it was vacuum as idle was fine. Replaced coil, leads, plugs, rotor arm, cap, but no difference. Was on the verge of replacing the injectors when I had a closer look at the larger gauge piping on the APC valve. Turned out the pipe between wastegate and APC solenoid had a split. Under acceleration the engine/turbo moved back on its mounts and moved the pipe as the APC solenoid was bolted to the bulkhead - split opened up, vacuum leak!
Gaffer tape confirmed, new pipe solved.
Months of hassle, swearing, replacing parts, considering selling, etc. Just shows that vacuum probs can manifest in all sorts of ways...
I would order some new piping from partsforsaabs and replace all you can - see how it runs after that. Will only cost a few quid and will save future problems.
This might sound a bit "noddy" so please forgive my ignorance!Boost leaks can be hard to track down - the only way is to look really closely at all the pipes - which can be a nightmare with some disappearing behind the bulkhead etc. I ended up replacing all the ones I could with silicone ones.
I had a problem with my c900 a couple of years ago, where when I accelerated I would suddenly completely lose power & kangaroo. Embarrassing and dangerous. Didn't think it was vacuum as idle was fine. Replaced coil, leads, plugs, rotor arm, cap, but no difference. Was on the verge of replacing the injectors when I had a closer look at the larger gauge piping on the APC valve. Turned out the pipe between wastegate and APC solenoid had a split. Under acceleration the engine/turbo moved back on its mounts and moved the pipe as the APC solenoid was bolted to the bulkhead - split opened up, vacuum leak!
Gaffer tape confirmed, new pipe solved.
Months of hassle, swearing, replacing parts, considering selling, etc. Just shows that vacuum probs can manifest in all sorts of ways...
I would order some new piping from partsforsaabs and replace all you can - see how it runs after that. Will only cost a few quid and will save future problems.
Having just changed the fuel filter (checked back over the history I keep for it, and it turns out I hadn't changed it, so have just done now), it hasn't really made any difference.
Looked around for about an hour until I realised my car does not have a MAF sensor
so that's one less thing to worry about.Then I moved onto what you said - the hoses, in particular the small bore hoses. The one that goes from the wastegate to the inlet manifold is really brittle and crappy. I presume that if this weeps pressure, it could cause my running issues?? How would the MAP sensor react to this?
I will be buying some more hose tomorrow to replace it anyway but just wanted to know your thoughts
I'd hazard a guess that its the DI pack, they are one of the few weak points of these engines and seem to fail on older cars, its easily remedied, although they can be quite pricey for a genuine one, avoid the chinese patterns.
Also some people go for the black DI from the non turbo cars as they are cheaper and often more readily available, and from what I've heard have no issues, although I don't have first hand experience of this.
Also some people go for the black DI from the non turbo cars as they are cheaper and often more readily available, and from what I've heard have no issues, although I don't have first hand experience of this.
Garett said:
I'd hazard a guess that its the DI pack, they are one of the few weak points of these engines and seem to fail on older cars, its easily remedied, although they can be quite pricey for a genuine one, avoid the chinese patterns.
Also some people go for the black DI from the non turbo cars as they are cheaper and often more readily available, and from what I've heard have no issues, although I don't have first hand experience of this.
Hope it isn't the DI as I replaced this back at New Year (ie 7 months ago) with a brand new red top.Also some people go for the black DI from the non turbo cars as they are cheaper and often more readily available, and from what I've heard have no issues, although I don't have first hand experience of this.
NiceCupOfTea said:
Worth replacing any vacuum pipes that look dodgy - if they're not leaking now, they will.
Will do. Surely though, the pipe from the I don't mean the wastegate, in actual fact. There is a little black cylindrical item that is on the air pipe just after the airfilter, and it has a small bore hose that goes to the inlet manifold. What is it?? This is the hose which is perished.
Edited by Wing Commander on Thursday 8th July 20:33
Found it - its the bypass valve
Edited by Wing Commander on Thursday 8th July 20:34
Going by other turbocharged cars my guesses are:
spark plugs (I know you said you changed them, are they the correct gap? Try gapping down a little and see if it helps, if it does you may have a weak spark which could be:
HT Leads
Coilpack(s)
Ignitor/Ignition amplifier
otherwise I would say its a boost leak, soapy water sprayed against boost pipes is a good trick, then give it some hard revving to get enough air through to see any bubbles. Intercooler if its not the pipes, or the clips arent tight enough.
spark plugs (I know you said you changed them, are they the correct gap? Try gapping down a little and see if it helps, if it does you may have a weak spark which could be:
HT Leads
Coilpack(s)
Ignitor/Ignition amplifier
otherwise I would say its a boost leak, soapy water sprayed against boost pipes is a good trick, then give it some hard revving to get enough air through to see any bubbles. Intercooler if its not the pipes, or the clips arent tight enough.
Marquis_Rex said:
From all that you're written, it sounds like you have a 'tranient fueling' issue. This means that on transients, when you "tip-in' on the accelerator- like you have to when you change load to go up a hill or go faster- the Air fuel ratio is incorrect. It's unlike to be the incorrect grade of plug- as this kind of mis fire wouldn't just manifest itself only during transients, as you've indicated, but continually.
Not saying you are wrong, but with turbocharged cars this can happen as the higher load will make the turbo produce more boost which can show up any ignition weaknesses which may not occur off boost. 
Hmm, well I have replaced lots of the vac hoses with silicone ones and, whilst it didn't make any differences, I know its done now and the old ones were in a right state.
But the hesitation was still there. Well, today I was in the petrol station and I had a thought. Might as well try the tesco momentum 99 and see what it's like. No more hesitation and, although it might just be mind tricks, the car feels to be considerably perkier.
And there was me on the verge of spunking circa £100 on a new fuel pump. Happy days! Thanks everyone!
But the hesitation was still there. Well, today I was in the petrol station and I had a thought. Might as well try the tesco momentum 99 and see what it's like. No more hesitation and, although it might just be mind tricks, the car feels to be considerably perkier.
And there was me on the verge of spunking circa £100 on a new fuel pump. Happy days! Thanks everyone!
Boosted LS1 said:
The cure for mine was to regap the plugs to .038", about 1mm They had worn a bit and the gaps were quite large.
My plugs were new not that long ago, but I might pop them out and check the gaps, just to be sure. They had worn a bit and the gaps were quite large.After this, I will be investigating remapping the ECU to get me to Stage 1. Can't wait for a bit more poke!
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