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Discussion Starter #1
My '02 Aero is acting up.

It unfortunately sat for 18 months but has been on the road since August.
I am the 7th owner and god knows what happened under previous ownership....

I do not get full boost most of the time. Sometimes the car will give me full madhouse Aero boost and torque so I know it's there to give...

On the way home the other day, I was forcibly attempting to give the car full boost with aggressive throttle input. When I did get full boost I noticed smoke behind me but I cannot confirm what colour.. It looked more dark than white.

I have the following three codes which I pulled with my cheap OB2 reader:
  • P1110 = MAF Sensor Intermittent/ Check of all OBDII Systems
  • P0502 = Vehicle Speed Sensor Low Input (note: ABS fuse it pulled due to TCS issues)
  • P0134 = O2 Sensor Circuit No Activity Detected (Bank 1 Sensor)
I checked all vacuum lines and all appeared to be connected. My car does have a strong smell of burned oil coming from the engine bay but that may be due to the oil spray applied shortly before it was parked for 18 months. Oil bay is relatively clean with no sign of oil leaks anywhere.

I'm bringing my car to my friend's place on Sunday to use his lift. I hope by then I have a better idea of what this problem is. At first I thought the turbo is failing but I may have an intake/exhaust and/or electrical issue.

Thoughts?
 

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P1110 is MAF. It could cause boost issue.
P0502 is speed missing. This will prevent full boost.
P0134 front O2 sensor failure.
 

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Discussion Starter #3
Bump...

A friend and I worked on my car yesterday and performed the following:
1. Bypassed the boost solenoid located on the firewall. BCV now routes direct to the TB as per this: https://genuinesaab.com/gallery/albums/troll/T7Bypass.sized.jpg
2. Inspected ECU J16 splice. The splice looked clean but we cut and soldered a new connection.​
3. Tested BCV. Is operational.​
4. Cleaned MAF and TB. Both were quite dirty.​
5. Replaced accessible & functioning vacuum lines with new rubber vac lines.​
6. Discovered a bad check valve and replaced it with a temporary check valve my friend had kicking around. Replacement metal part on the way.​
7. Cleaned the electrical terminal that sits on top of the BCV solenoid. Some of the pins were corroded.​
After the work was completed the car started up much quicker then previous. All codes self-cleared. Full boost did not return, still in the mid yellow. P1658 came immediately, P0502 returned later on the drive home.

On the way to work this morning, I cleared all the codes and this allowed the boost to go full retard deep into the red. An hour later I made an errand and the boost was again limited to the yellow with P1658 returning immediately.

No signs of P1110 and P0134.

My friend suggests we next try the T7 bolt mod and/or replace the EVAP check valves as per this: How-to Fix the EVAP Check Valves (not the bolt mod)

Any thoughts and suggestions?
 

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Discussion Starter #4
Part 3!

Last Sunday my friend and I worked more on the vac/evap lines. Since then, all vac related CEL codes have been cleared and have not returned. After working on the car, I managed to get full boost and the power output felt very healthy. The following morning, again, limited boost in the mid yellow.

Since then, no CEL codes have returned however I have observed a gradual loss of power throughout the week.

On the way home this afternoon I attempted a few 2nd and 3rd gear pulls and got almost no power; the turbo struggled immensely to even touch the yellow. Lots of hissing sound as if I have a boost leak however the "boost leaking sound" appears to eminate from the rear half of the car and not upfront where the intake assembly is. During one pull in 3rd, WOT, the engine itself struggled to climb to 5000rpm. The smell of burning is stronger than ever (I originally thought it was oil under-spray since I have observed this smell since August) but this now appears to be the unlikely source. Hot/burning catalytic converter is likely...?

So at least I fixed all my vac related CEL codes however I think I have a bad catalytic converter....

Need some help/advice, please!
 

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Easiest way to check the cat is use a digital thermometer and check the inlet temperature at the cat and check the outlet temperature after the cat the temperature after the cat should be about 100 degrees less then the inlet.

Is your car burning oil or are you driving with a lot of misfires?
.
 

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Discussion Starter #6
Is your car burning oil or are you driving with a lot of misfires?
I don't believe the car is burning oil in the combustion phase because the exhaust appears to be clear of blue smoke.
There is some occasional hesitation when the engine is under load (they feel like misfires) but I'm not getting any codes. When I removed the MAF to clean it I observed some oil buildup inside the metal inlet pipe that leads from the MAF down to the turbo. There's also some oil around the throttlebody; I assumed that was caused by the failed check valve..

I read elsewhere that a cat doesn't typically fail on its own; failure is caused by another underlying problem. I did have an O2 sensor code as per above.... There may very well be an oil leak somewhere in the intake/turbo... Speculation on my part for the time being.

I have a laser thermometer at work and since I'm going to work early tomorrow morning I will check for red hot glowing cat and also take temperature readings.
 

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Ya, cats don't die/clog without pretty significant ingestion of the wrong stuff.

If the turbo is on it's way out it can send quite a bit of oil downstream without too much smoke.
 

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those cats can ingest a LOT of oil and still be good. When my son's Garrett Turbo blew the turbine shaft split and it dumped a ton of oil into the exhaust. like there was liquid oil coming out of the cat when I took it off.

When we started it up and the cat got warm it smoked like crazy. Took it for a long ride when it was dark out and after about 20 minutes all was good. I was worried that it wasn't going to pass the CA smog test when it came up, but no problem.

Unburnt fuel from misfires on the other hand is a real problem.
 

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My '02 Aero is acting up.

It unfortunately sat for 18 months but has been on the road since August.
I am the 7th owner and god knows what happened under previous ownership....

I do not get full boost most of the time. Sometimes the car will give me full madhouse Aero boost and torque so I know it's there to give...

On the way home the other day, I was forcibly attempting to give the car full boost with aggressive throttle input. When I did get full boost I noticed smoke behind me but I cannot confirm what colour.. It looked more dark than white.

I have the following three codes which I pulled with my cheap OB2 reader:
  • P1110 = MAF Sensor Intermittent/ Check of all OBDII Systems
  • P0502 = Vehicle Speed Sensor Low Input (note: ABS fuse it pulled due to TCS issues)
  • P0134 = O2 Sensor Circuit No Activity Detected (Bank 1 Sensor)
I checked all vacuum lines and all appeared to be connected. My car does have a strong smell of burned oil coming from the engine bay but that may be due to the oil spray applied shortly before it was parked for 18 months. Oil bay is relatively clean with no sign of oil leaks anywhere.

I'm bringing my car to my friend's place on Sunday to use his lift. I hope by then I have a better idea of what this problem is. At first I thought the turbo is failing but I may have an intake/exhaust and/or electrical issue.

Thoughts?
If any of the two faults are present ABS and or TCS in your case, car won't fully boost.
 

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Any time the CEL is on, I would assume there will be diminished performance.

I fixed my P1110 by replacing the diverter valve. It's pretty easy to check, you can start by applying a vacuum to the nipple and see if it sounds like anything is moving in there.

P1658 points again to diverter valve and its controls.

Your mods to the turbo wastegate won't help if the bypass valve is leaking. It may even mask the problem from the ECU (more boost from the turbo than it expects, but leaking around the valve).
 
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