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Now that I've got the car started and running, it was doing pretty well. I noticed some throttle response lag and it was a bit gutless. Up until yesterday, the only issue I had was the same old EVAP leak code (I think it's the purge solenoid). However, after sitting in the parking garage at work all day, i started her up to drive home and something was wrong.
I ran Torque and I see the LTFT and STFT for both banks maxed out. +25% STFT, +19.5% LTFT. I've got codes for both banks Lean, and either a 0420 or 0430 for cat efficiency below threshold. At 1500rpm and highway speeds, the trims go down, but not to anywhere close to zero. Total trim on both banks is generally >15%, still. Also, calculated engine load jumps from 40% to >80% at part throttle, like accelerating up a freeway ramp, and I hear a loud whooshing sound which seems like it's coming from a couple of feet behind the center of the dashboard - so somewhere in the engine compartment. Mind you, this is not accompanied by the level of thrust and acceleration you'd expect; it is struggling to accelerate (for an STR, it's probably fast for an econobox, still). It's not the typical supercharger whine - which is still audible, but the whoosh is much louder. Under no load, like revving while stationary, I don't get this sound. Yesterday, while listening and diagnosing what was going on while commuting home, the car consumed nearly a quarter of a tank. This morning, I stayed away from that throttle position where I heard the whooshing, and my fuel consumption was reasonable.
So, where do I start? Downstream sensors, or go for the full cat replacement? A little history, if you're new to my car: I had a failed fuel rail pressure sensor that was causing a no-start issue. The cylinder bores sat with fuel in them for a while, drained into the oil. When I finally got it started it was blowing huge amounts of smoke. I changed the oil and that cleared up and it started running better and better. However, I started getting fuel consumption issues a couple weeks before (poor gas mileage).
With that in mind, is it more likely an O2 sensor issue, or a blocked/broken cat?
At least try the advice so endlessly posted (Search is your tool) about checking for air leaks.
With faults it's never going to drive as it should so stop expecting it to do so before they're fixed.
I already have a date with a friend and his big shop to test for air leaks. I have a smoke machine.
I'm just asking if there's anything else I should be considering, especially the catalyst efficiency issue that doesn't seem to have a definitive answer here on the forums. People say it's caused by a variety of things, there's differences in information about whether the downstream sensor is used for trims, and so forth. I'm trying to disambiguate by requesting the latest and most relevant information instead of plowing through a decade of posts to build up a current, consistent knowledge base.
I'm just asking if there's anything else I should be considering, especially the catalyst efficiency issue that doesn't seem to have a definitive answer here on the forums. People say it's caused by a variety of things, there's differences in information about whether the downstream sensor is used for trims, and so forth.
That's because most errors have multiple possible causes as you can see from the workshop manual.
It also tells you about what the downstream sensors are used for (yes, trims).
It's a lot faster to read what it says than post questions and wait for someone else to refer to it for you.
That's because most errors have multiple possible causes as you can see from the workshop manual.
It also tells you about what the downstream sensors are used for (yes, trims).
It's a lot faster to read what it says than post questions and wait for someone else to refer to it for you.
We're not all as adept as you at interpreting the workshop manual
The thing that's frustrating me is unraveling multiple overlapping failures that mask or simulate other failures. That drives me crazy.
The good news, though, is that I smoked the vacuum lines and found the induction elbow gasket is leaking like that's its job. Dealer had one in stock, so I'm going to replace it this evening.
That will just leave - hopefully - the EVAP leak. After I get the gasket replaced, I'll take a breather then do another pass with the smoke machine. If I see no leaks, I think (hope) it's fair to believe that the purge solenoid is dead. I believe that's the one up by the charcoal canister, right? Above the differential? I sure wish it was located where the XK has it, and easier to get to...
HAhahahahaha.... Of course that's not the end of the air leaks. I replaced the gasket - which was deteriorated and falling apart (see pic).
Afterward, the trims, instead of being firewalled positive, were only merely REALLY high. ST+15, LT+19. Drove it around for about a half hour, fast, slow, everywhere in between. Got home and took the propane to the area where I could now hear a hiss, and I believe I have a leak in the intake runner gaskets between the intercooler and head on Bank 1.
At the risk of drawing some ire: I need to ask if anyone has a diagram of the intercoolers, induction headers, inlet manifold w/injectors for a 2005 STR.
Bonus points to anyone who has removed one, and knows about all the gaskets involved. I imagine there are gaskets between the induction headers and the inlet manifold, and another set of gaskets between the inlet manifold and the head. Are the fuel injectors a metal-on-metal seal, or are they also fitted with gaskets?
If there is a gasket master set that contains all this hoopla for both banks, I'll get it. Save me some headache?
attacht your elm and run a program where you can look at the fuel trims as a graph. take a tin of brake cleaning fluid and spray it around the engine bay have somebody look to see when there is a change in the fuel trims. This will tell you where there is an air leak.
attacht your elm and run a program where you can look at the fuel trims as a graph. take a tin of brake cleaning fluid and spray it around the engine bay have somebody look to see when there is a change in the fuel trims. This will tell you where there is an air leak.
Already did that . That's now I know it's coming from somewhere in between the intercooler(s) and the head(s). The leak is worse on the Bank 1 side, but there is a small leak on the other side as well. I've got a flexible borescope coming, so I can see down in there. Once it arrives, I'll smoke the system again.
I have removed the SC twice before on my 2005 STR. Try this post as I referenced a lot of good links I think would help you. Do you know about the hose under the SC? Your already most of the way there to change it.
These threads have a bunch of pictures showing the engine during disassembly as well as a number of tricks for removing the SC and EGR.
The real question to ponder is why do the fuel trims increase with air leaks on both sides of the blower? Un-metered air entry?
Presumably, yes. When I smoke tested it before, there was so much smoke coming out from between the top of the SC and the induction elbow that it obscured any other leaks.
I can only assume that when I smoke test again, that I'll see similar (smaller) leaks bilaterally. I'll fix whatever I find
I have removed the SC twice before on my 2005 STR. Try this post as I referenced a lot of good links I think would help you. Do you know about the hose under the SC? Your already most of the way there to change it.
These threads have a bunch of pictures showing the engine during disassembly as well as a number of tricks for removing the SC and EGR.
Presumably, yes. When I smoke tested it before, there was so much smoke coming out from between the top of the SC and the induction elbow that it obscured any other leaks.
I can only assume that when I smoke test again, that I'll see similar (smaller) leaks bilaterally. I'll fix whatever I find
Ken
I guess I miss phrased it. During vacuum conditions you'd let unmetered air in the engine but under boost you would be pushing metered air out of the system. Boost is more dependent on load than RPM so I suspect if you were running boosted that it would blow a ton of gray / black smoke from the fuel trims so rich to compensate for the unmetered air under vacuum conditions.
On my '07 XKR I had catalyst efficiency codes with 200 cell cats but got downstream o2's lazy with a pair of 2011 5.0 Mustang cats. It's curious what codes the ECU will throw given differing situations and how important it is to trust basic mechanics to help troubleshoot a problem.
I feel like you're trying to tell me something about my assumptions or the direction I'm headed. JagV8 has lit me up plenty about doing anything other than fixing the problems pointed to by the codes. This post thread, unfortunately, is a misnomer. The lean condition is a bigger problem right now than catalyst efficiency.
I've gone through already and used brake parts cleaner to determine where the worst vacuum leak offenders are - roughly. Still need to do another smoke test to spot the next big leak.
I suspect that, in addition to the induction manifold gaskets, that little hose that attaches to the induction elbow is probably trashed. Also, there's a good chance that the brake booster to throttle body hose is leaking (they all seem to fail eventually). I'm content to work my way up from the low-hanging fruit (big leaks)...
The flexible/extensible flange seal that goes between the SC outlet elbow and the Bank 1 intercooler is leaking. It may not have been, actually, but I had to remove it to get the intake off, which broke the seal. That explains part of the vacuum leak. The other part (Bank 2) is something on or near the throttle body. I suspect brake booster hose. This was all discovered through propane and brake parts cleaner. I'll have to wait a little bit for a smoke test because my air compressor decided to stop working.
I'll order the SC outlet elbow seals. I already have the stupid brake booster hose seal kit, so there's that.
06-15-2017 | 03:09 PM
05 STR Catalyst Efficiency issues
. Thanks for the helpful videos!
