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Hi guys,

I had posted last year about my car seemingly bogging down and pulling timing, especially in warmer weather. There's not a definitive fix. Suggestions were to install an aftermarket intercooler or check the DIC and other ground points. I tried running a ground wire from the battery to the thermostat but the issue remained.

Well, funny thing. This summer, it has started to get hot here in MN. It was 95F yesterday with tropical levels of humidity. I've had no issues this season at all, even on the hottest days with the A/C on max. The car still boosts into the red when I punch it. Feels SO MUCH BETTER than last year.

So why would it heatsoak/pull timing one year and not another? Who knows! The only thing that has changed in the last couple months is the BP by my house where I usually fill up became a Holiday. Do you think the BP was selling sub-par premium gasoline, and the Holiday stuff is better?

This remains a mystery. I am running a "cooler" plug - NGK BCPR7ES (6282) but I was running those last year too. Nothing has changed.
 

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Hi guys,

I had posted last year about my car seemingly bogging down and pulling timing, especially in warmer weather. There's not a definitive fix. Suggestions were to install an aftermarket intercooler or check the DIC and other ground points. I tried running a ground wire from the battery to the thermostat but the issue remained.

Well, funny thing. This summer, it has started to get hot here in MN. It was 95F yesterday with tropical levels of humidity. I've had no issues this season at all, even on the hottest days with the A/C on max. The car still boosts into the red when I punch it. Feels SO MUCH BETTER than last year.

So why would it heatsoak/pull timing one year and not another? Who knows! The only thing that has changed in the last couple months is the BP by my house where I usually fill up became a Holiday. Do you think the BP was selling sub-par premium gasoline, and the Holiday stuff is better?

This remains a mystery. I am running a "cooler" plug - NGK BCPR7ES (6282) but I was running those last year too. Nothing has changed.
Have you replaced your T Stat or Coolant Temp sensor?
 

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My '07 still bogs, has done so since I bought the car 5 years ago. Stumped every mechanic I talked to. Aluminum IC and octane boosters help a bit, as did a new BCV. But the issue is still there after stop-and-go city driving (or short parking stints) in 90+ degree temps. No power below 3000 rpm and needle doesn't go into the red. Takes ~10 seconds to reach 30 mph at full throttle. I'm running the BCPR7ES plugs as well. New MAF didn't solve the issue and neither did a new TB.


OBD2 logs did not show exceedingly high intake temps when the hesitation occurs. The one constant I found was that once IAT got over 120-130ish (even if only briefly), the ECU would pull boost for the remainder of the trip even if the intake temps thereafter lowered due to high-speed driving. Only a full 3+ hour engine cooldown would result in the car driving normally.


Also, duing the bogging, the OBD2 logs shows ridiculously high engine load (near or at 100%) and Manifold Throttle Body Position of only 30-40% despite me pressing the acceleration at near maximum.


The amazing thing is that below 80 degrees, car is a rocket 100% of the time. Turbo boosts well into the red and I can spin the tires in 2nd gear...
 

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When I lived in California in an area that routinely would reach over 100 during the day but with very low humidity I never noticed this.

Now that I'm in Pittsburgh where I see 90-degree days with lots of humidity I see it all the time.

I wish I understood just what is going on though.
 

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Discussion Starter #6 (Edited)
When I lived in California in an area that routinely would reach over 100 during the day but with very low humidity I never noticed this.

Now that I'm in Pittsburgh where I see 90-degree days with lots of humidity I see it all the time.

I wish I understood just what is going on though.
The strangest part is how this summer, which has been extremely hot and humid so far by MN standards, the issue has seemingly disappeared. The car boosts and pulls even in 95F super humid weather. As I mentioned in my original post in this thread, the only change has been the BP where I normally fill up changed to a Holiday. Do you think this particular BP was selling sub-par premium fuel, and the Holiday stuff is better?
 

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The strangest part is how this summer, which has been extremely hot and humid so far by MN standards, the issue has seemingly disappeared. The car boosts and pulls even in 95F super humid weather. As I mentioned in my original post in this thread, the only change has been the BP where I normally fill up changed to a Holiday. Do you think this particular BP was selling sub-par premium fuel, and the Holiday stuff is better?
I would not be surprised, since I do notice a slight improvement if I mix in some octane booster or a couple gallons of race fuel. Perhaps something akin to vapor lock is happening?


Humidity doesn't seem to matter, I live in a desert where it's 100+ degrees every day for the better part of 3 months but bone dry and the hesitation happens virtually daily.
 

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The strangest part is how this summer, which has been extremely hot and humid so far by MN standards, the issue has seemingly disappeared. The car boosts and pulls even in 95F super humid weather. As I mentioned in my original post in this thread, the only change has been the BP where I normally fill up changed to a Holiday. Do you think this particular BP was selling sub-par premium fuel, and the Holiday stuff is better?
Could be ethanol is used even in the premium BP gas which might be causing your issues and possibly the Holiday premium gas doesn't have any ethanol in it.
 

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Sounds like an electrical gremlin. Mines an 07 and I live in an area that experiences extremely hot and humid summers. On one very hot and humid day, I raced a mustang GT and won. I will be honest and say he had a very rough start, but still, he never caught up, the 9-5 pulled hard that day. This was possible with no modifications, just good plugs, gas and oil. So if you're just throwing parts at it trying to fix it, maybe just stop and save your money. All that I can think of is to fix each of the grounds, sand them down, put on the vaseline wis recommends.
 

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I was thinking about this thread this morning on my way into work. Prior to picking up my 9-5s I haven't run petrol turbos for years. Thinking back my last quickish petrol turbo was an A3 Quattro around 2008. But I do clearly remember looking forward to colder mornings when I knew the car would perform well, as it did this morning. From cold my 9-5 always feels great but after a bit of town driving it's not such a nice place to be. Then back on some fast A roads with the air flowing and the car's performance returns.

As an aside, changing the coolant is on my list of jobs as this car came with no history. I wonder if that will make any noticeable difference?
 

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As an aside, changing the coolant is on my list of jobs as this car came with no history. I wonder if that will make any noticeable difference?

I doubt it, I refreshed my car's coolant when I changed my water pump about a year ago and it made no difference. Additionally, even when the hesitation happens, coolant temps are quite low, hovering around 210F.
 

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two 9-5s in my family, an 03 linear with td04, 3" exhaust and jzw stage 3 tune, and a stock 08 aero. both of them have the same issue. both have the stock intercooler. both have newish bcpr7es plugs, new NGK labeled SEM DI cassettes, new OEM temp thermostats.

with opensid on the 03, i can see iats hitting 68C, and ioff hitting -250. i dont have opensid in the 08, but i assume it's hitting similar numbers. when this happens the car will hardly even accelerate, to the point of being dangerous.

has anybody had luck fixing this?
 

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Discussion Starter #15 (Edited)
two 9-5s in my family, an 03 linear with td04, 3" exhaust and jzw stage 3 tune, and a stock 08 aero. both of them have the same issue. both have the stock intercooler. both have newish bcpr7es plugs, new NGK labeled SEM DI cassettes, new OEM temp thermostats.

with opensid on the 03, i can see iats hitting 68C, and ioff hitting -250. i dont have opensid in the 08, but i assume it's hitting similar numbers. when this happens the car will hardly even accelerate, to the point of being dangerous.

has anybody had luck fixing this?
I wouldn't say I have fixed it, but as I mentioned in my original post, this summer I haven't had any issues with low boost. It got really hot last week--like 95F and 60s humidity, and the car pulled fine (turbo gauge part way into the red) even after stop and go traffic.

The only change has been the brand of gas. The BP in my neighborhood changed over to a Holiday. Did BP have subpar fuel? Maybe try changing fuel brands just for fun.

Last summer I took the front bumper off and cleaned the radiator/intercooler/evaporator coils. The radiator was somewhat full of cotton/bugs/etc. I used Coil Clean (a spray) and sprayed it all down with a hose. That was probably in July or August of 2018, but the car still bogged for the rest of that summer (like yours, it was downright dangerous in an acceleration situation). So I truly don't know what the deal is, and why it's now gone. It'll probably come back, which is why I'm hesitating to call it "fixed."
 

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BP is Top Tier gas, so that shouldn’t be the issue. This issue is very puzzling...? Seems like a lot of the bases have already been covered. So weird. :confused:
 

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Update: I just wrapped as much as I could of my intake tubes (both pre- and post-intercooler) with Reflect a Gold tape a few days ago and so far results are encouraging. Was 102 degrees today and had numerous short errands to run and, although I felt maybe a 10-15% power loss after a while, it was nothing compared to the extreme hesitation of before. Time will tell if the problem truly is resolved. Fingers crossed.

As an aside, the brake booster vacuum pump that sits right below the plastic intake tube was incredibly HOT even hours after turning off the engine. Not sure if that's normal and surely it can't be good for intake temps.
 

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Update #2 (since I can't seem to edit my previous post)

SOLVED! Adding reflective tape did help lower my intake temps by a few degrees (as did the do88 IC), but 2 gallons of E85 on every fill-up has COMPLETELY eliminated the hesitation. Octane boosters or race gas helped only partially/marginally. My guess is that the hesitation is caused by high cylinder temps and ethanol burns significantly cooler. I checked my data logs recently, and there is no more negative ignition offset and knock counts are FAR lower. Also, AFAIK my E20 mix is perfectly safe long-term, although I certainly wouldn't go higher than 2 gallons of E85 per full tank due to the risks of running overly lean.

Hope this helps those that are still chasing this problem, I know there were quite a few threads over the years about this with no real solution.
 

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Update #2 (since I can't seem to edit my previous post)

SOLVED! Adding reflective tape did help lower my intake temps by a few degrees (as did the do88 IC), but 2 gallons of E85 on every fill-up has COMPLETELY eliminated the hesitation. Octane boosters or race gas helped only partially/marginally. My guess is that the hesitation is caused by high cylinder temps and ethanol burns significantly cooler. I checked my data logs recently, and there is no more negative ignition offset and knock counts are FAR lower. Also, AFAIK my E20 mix is perfectly safe long-term, although I certainly wouldn't go higher than 2 gallons of E85 per full tank due to the risks of running overly lean.

Hope this helps those that are still chasing this problem, I know there were quite a few threads over the years about this with no real solution.
Good to hear. The higher octane rating is surely helping you out, especially in hot weather. Modern cars can dial upwards of 5+ degrees of additional timing advance while running FlexFuel over the normal pump gas advance table. In your case, you’re getting to keep the full regular pump gas advance, which is obviously good. At E20, you’re not getting much of a cooling effect on the cylinder charge, but some effect is better than none.

Most factory tunes are incredibly rich at WOT and high engine IATs. Leaning it out a tick generally gives a small power boost too. But you’re smart to keep it conservative on how much E you dump in... ;)
 

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Discussion Starter #20
Update #2 (since I can't seem to edit my previous post)

SOLVED! Adding reflective tape did help lower my intake temps by a few degrees (as did the do88 IC), but 2 gallons of E85 on every fill-up has COMPLETELY eliminated the hesitation. Octane boosters or race gas helped only partially/marginally. My guess is that the hesitation is caused by high cylinder temps and ethanol burns significantly cooler. I checked my data logs recently, and there is no more negative ignition offset and knock counts are FAR lower. Also, AFAIK my E20 mix is perfectly safe long-term, although I certainly wouldn't go higher than 2 gallons of E85 per full tank due to the risks of running overly lean.

Hope this helps those that are still chasing this problem, I know there were quite a few threads over the years about this with no real solution.
And there's no harm with adding a couple gallons of E85 in the long run? I know with internals that aren't designed for it, E85 can be corrosive. But perhaps a couple gallons isn't a big enough deal.
 
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