SaabCentral Forums banner

1 - 20 of 40 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
OK, a problem so intermittent, it's only happened 8 times in 3 or so years, but it sucks and it continues: My car goes into serious no-power limp mode abruptly and temporarily. My Saab specialist of 30+ years is stumped.

Symptoms: No power whatsoever. If I try to accelerate beyond I-have-an-egg-under-my-foot pressure on the gas pedal, it just bogs down and won't go. With this super light foot pressure, I can get up to about 2000 rpm, then I have to shift into second. Getting into 3rd or 4th is really difficult. If I can get up into those gears (flat roads only) and give it any gas, it shudders and bucks horribly and slows down. Only with the lightest pedal pressure can I keep going. On the freeway, where it's happened most often, gas mileage plummets by 30-40%. The only cure seems to be stopping for a while and letting it cool off, sometimes while it idles, more often only by shutting it down and waiting a bunch. CEL comes on, sometimes flashes as it does. Codes have been 0300 random misfire, 1171 lean mixture, 0171 bank 1 too lean, but those have been days later.

After it cools down, which usually ends up being overnight, it drives just great for months. It's a fine machine otherwise, (SS cat back exhaust, intercooler, JSW stage 3 tune). My mechanic can't find anything amiss. And it won't happen again for months. Only common thing seems to be that it occurs in hot weather, although the engine is running normal temps. 3 of the last 4 times, it's happened on the freeway after running hard for 2-4 hours or so. I'd be hugely grateful for any help.
 

·
Registered
Joined
·
1,080 Posts
Fuel pump been replaced within the past 50k?
If not start there, the things are affordable.. and few replacements live as long as the factory fitted ones.
 

·
Registered
Joined
·
2,015 Posts
OK, a problem so intermittent, it's only happened 8 times in 3 or so years, but it sucks and it continues: My car goes into serious no-power limp mode abruptly and temporarily. My Saab specialist of 30+ years is stumped.

Symptoms: No power whatsoever. If I try to accelerate beyond I-have-an-egg-under-my-foot pressure on the gas pedal, it just bogs down and won't go. With this super light foot pressure, I can get up to about 2000 rpm, then I have to shift into second. Getting into 3rd or 4th is really difficult. If I can get up into those gears (flat roads only) and give it any gas, it shudders and bucks horribly and slows down. Only with the lightest pedal pressure can I keep going. On the freeway, where it's happened most often, gas mileage plummets by 30-40%. The only cure seems to be stopping for a while and letting it cool off, sometimes while it idles, more often only by shutting it down and waiting a bunch. CEL comes on, sometimes flashes as it does. Codes have been 0300 random misfire, 1171 lean mixture, 0171 bank 1 too lean, but those have been days later.

After it cools down, which usually ends up being overnight, it drives just great for months. It's a fine machine otherwise, (SS cat back exhaust, intercooler, JSW stage 3 tune). My mechanic can't find anything amiss. And it won't happen again for months. Only common thing seems to be that it occurs in hot weather, although the engine is running normal temps. 3 of the last 4 times, it's happened on the freeway after running hard for 2-4 hours or so. I'd be hugely grateful for any help.
Might want to try a new crank position sensor.

http://www.saabcentral.com/forums/showthread.php?t=178921&highlight=highway
 

·
Registered
Joined
·
301 Posts
I agree CPS is somethign to try; I understand it is one of the things that can stop working when hot and works when cools down. but i thought it would shut down engine rather than make it run badly. I would try a known good DIC also. someone locally may have one you can borrow (my car came with 3 spare DIC from the PO).

fuel pump also sound possible. between those 3 things good chance problem woudl be resolved.
 

·
Registered
Joined
·
1,080 Posts
Before replacing the CPS 'on spec'
With the knowledge that the last model 9000's were fitted with an easy to get to / replace proven surprisingly reliable CPS gizmo..
Test it for the Heat theory ??
Get a can of 'Freeze it' from an electronics shop (used to spray cool electro bits for temperature failures) And try/see if spray cooling the CPS makes the car instantly revive?
Except for obtaining the freeze it... a V quick easy Test.
 

·
Registered
Joined
·
3,938 Posts
I'd be looking at the air bypass hose where it fits under the throttle housing. The brass nipple comes unglued and leaks air. It can also fail to remain in place but intermittently. When you look at it with the engine off it can seem ok.

Glue it back in or secure it with cable ties.
 

·
Registered
Joined
·
3,014 Posts
Temp related drivability issues like you describe I would be looking at my CPS first like Chegny suggests. The CPS is the heart of T5. A bad CPS signal with effect ignition timing, spark, and fuel delivery.

Next, I would look at your direct ignition cassette. Remove it inspect it for oil leaks, melted plastic, and the smell of burnt electronics. If you have a known good spare...you could try swapping it in.

Next, I would check you oxygen sensor for any for any damage to its wiring.

Lastly, I would inspect the wiring to your fuel pump. Both psychically and electrically. You're looking for damaged insulation/corroded earth points and with a multimeter for continuity and voltage.

***Fuel pumps do not show failure in the manner describe and an air leak no matter how big would have no effect engine performance in the manner described.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #8 (Edited)
Thanks all, for your suggestions.
@davide c: Sorry to be late on the response, but had to go dig to find out I did get a fuel pump replaced Dec. 2014. On John Williams' suggestion, went with a Aeromotive 340 Stealth fuel pump with the center pick up. So that's 2 1/2 years ago. Maybe just about 50k miles. How would you expect it would be failing? Does all that gas get so hot (and maybe a not-full tank if I've been driving 2+ hours.) that the pump just seizes up?

@chengny: Still has original CPS in it. Will get that changed Tuesday, thanks, although my guy (Mike at MSN Auto in Salt Lake, a stellar mechanic) suggested that the engine would just die and not start again. Nevertheless, will change it.

@schumi: Put new DIC in last year or year before, will check with Mike on this, thanks.

@Superaero: Will take a look at that and discuss with Mike on Tuesday when I'm in, thanks also.

@davide c #2: This is sadly hysterical, but the damn thing just happened again 30 minutes ago. Drove 1.75 hours on fwy, did some big boosts, accelerations confirming the car runs normally (yes, just flies), got back in town, headed to neighborhood (2 miles) and IT DIED AGAIN! Luckily we had our mtn bikes and just biked home. BTW, it's 100 F here today. OK, this is now 2X in 4 days, suddenly frequent. I'm off to go get some freeze spray...

@dmgb5: Thanks, will check these out on Tuesday.

Optional question for y'all: Just wondering how the heat/hard running would affect all these items, and then, how the cooling off allows it to then run again? Not important, just wondering for my curiosity. No matter, will check out all of your good ideas. Thanks!
 

·
Registered
Joined
·
2,015 Posts
@chengny: Still has original CPS in it. Will get that changed Tuesday, thanks, although my guy (Mike at MSN Auto in Salt Lake, a stellar mechanic) suggested that the engine would just die and not start again. Nevertheless, will change it.

I used to believe that was true as well - but I have since learned differently:

DTC 0335:

Symptom Of Fault .
The engine fails to start or misfires.Other diagnostic trouble codes (misfiring, camshaft position).

NOTE: More diagnostic trouble codes will be generated if pin 67 of the control module is not connected to ground.

Conditions .
Vehicle speed > 19 mph (> 30 km/h)
Engine speed > 1500 rpm.
Brakes not applied.
The sensor reads an incorrect number of ribs (teeth) per crankshaft revolution.

Diagnostic Help .
The diagnostic trouble code often indicates an intermittent fault.
In the event of a complete functional breakdown, the engine will not. start and the diagnostic trouble code cannot be generated.

If the perforated ring, which is mounted on the crankshaft, has been damaged in connection with work carried out on the basic engine, for instance, the diagnostic trouble code may be generated.


Optional question for y'all: Just wondering how the heat/hard running would affect all these items, and then, how the cooling off allows it to then run again? Not important, just wondering for my curiosity. No matter, will check out all of your good ideas. Thanks!

I think it's simply because the CPS lives in the suckiest place in the engine compartment. All the heat thrown off by the heat exchanger stack is constantly blasted at it by the main cooling fan. Then there's all the oil that leaks down onto it from the distributor delete plug. Just those two conditions alone are enough to beat the hell out of the coax cable that connects it to the ECM. That's my theory anyway.
 

·
Registered
Joined
·
1,080 Posts
Sooo replace the CPS then :roll:
Easy/cheap enough to do. Might even work.. or not :)
Although Not what I would do... without proof .
Repairs 'on spec' due to Internet wisdom are Sketchy adventures IMO.
But Hey!! an Alldata subscription clearly trumps all intelligent thoughts.
 

·
Registered
Joined
·
2,015 Posts
If, at some point, he is lucky enough (to catch it when the engine is unable to pick up the load - and won't rev over 2000 RPM) here is a quick, yet very definitive two step test to identify a lost signal from the CPS. The first step (main relay check) is actually just a setup for the CPS test which is the second part:


Check the main relay

Since the main relay supplies the injectors and ignition discharge module with power, check its operation as follows:

Ignition switch in the OFF position.
Connect the test lamp to pins 10 and 6 of the ignition discharge module's connector.
Remove fuse 23 for 5 seconds.
Insert fuse 23.

Ignition switch in the ON position - check that the test lamp lights up for about 6 seconds and then goes out. Does the test lamp light up for 6 seconds?

YES:
The main relay is OK


NO:
See Fault diagnosis, "main relay".

Run the starter motor when the test lamp has gone out
The test lamp should then light up again.

Test lamp on?
YES
The crankshaft position sensor is OK
 

·
Registered
Joined
·
11 Posts
Discussion Starter #12
Thanks, Chegny. This is the same sequence and illustrations you showed here, I think. ...forums/showthread.php?t=271441

Very helpful. Will be prepared to check that the next time it dies.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #13
An the winner is...fuel pump!

Amazingly, the Silver Bullet had another heart attack, yesterday. We're talking 3 failures in 8 days, versus the previous 4 or 5 in 2.5 years. This was in town (for once!) so I limped into MSN Auto. Mike Newbold threw a fuel pressure gauge on it and bingo, no pressure (well, ~1/2 bar, 7 psi). New fuel pump (Walbro) going in today. So is a new CPS, since enough of you suggested that could be failing that I figured it was time to replace it too. (Car has 180k on it, although the engine was rebuilt in 2013.)

Will check all the wiring near the pump to be sure it's not frayed or anything, but right now it looked OK when I was watching him test it.

Interesting that the Aeromotive 340 Stealth failed (briefly) 7 months after installation, then started to fail more often another 10 months later, again, in the summer on a long hot trip. I've read of fake pumps on the market, but this was from a reliable supplier (Summit Racing) so don't know what to make of all that.

Mike thinks this was occurring on hot days, particularly after driving for some hours, when the gas tank is ~ half full or so, because the pump was heating up and somehow binding up. Once more gas got added, and we let the car sit for awhile, it would start and run merrily because it had cooled down and somehow it freed up again. No incidences ever in the cooler months.

In any case, thanks to everybody for your tips and suggestions. You're a great community!

Dimitri
 

·
Registered
Joined
·
11 Posts
Discussion Starter #15
Totally forgot that the fuel recirculates and could heat up in the process. Makes perfect sense as another mechanism to heat the pump up. Thanks.
 

·
Registered
Joined
·
3,938 Posts
Some newer cars just recirculate over pressure fuel supply within the engine compartment. Our older cars just recirculated bypassed pressure back to the tank. When the fuel levels got very low and the weather was hot the fuel tank contents could get very hot. Fuel pump failure often attributed to low fuel levels was really caused by very hot fuel. The pump is cooled by the fuel in the tank. On hot days when not using lots of power it pays to keep the tank fuller if you can, don't let it get really low.
 

·
Registered
Joined
·
3,938 Posts
I claim : nonsense.
Crap pump failed, as do most all aftermarkets.
And yet I have replaced only one fuel pump in the four SAABs I have owned. That's over 500,000 km and only one pump failure.

The pre pump in my 86 9000 failed on a very hot day when the fuel tank was nearly empty. The main pump kept going so I could get back home as long as the fuel tank had plenty of fuel in it.

My SAAB Master Tech diagnosed the fault over the phone citing several failures of the same kind from the same cause. SAAB changed the pump spec and solved that issue.
 

·
Registered
Joined
·
1,121 Posts
Heat does wired things to electrical; perhaps the ECU system itself becomes over loaded with problems and shuts down after an old fuel pump inner windings or an old CPS inners whatever they are give an odd signal, so I would replace both of those and see. That kinda sounds like what you did, so please post the outcome, so we all get the skinny!
 

·
Registered
Joined
·
11 Posts
Discussion Starter #20
Have now changed the fuel pump to a new one (Walbro) and the CPS to a new one. Won't know for sure that the problem is solved until I get it on the road for a couple of hours under load on a hot day. Will likely do that this weekend on a trip to Wyoming and will let you all know how it goes. Then, the following weekend (of the 22nd) will go to Idaho on a trip requiring 8+ hours of driving when it's usually pretty hot. That's when it's always happened and that will be the proof. Will report on that too.

D.
 
1 - 20 of 40 Posts
Top