GT failed AirCare, need advice. |
Post Reply | Page 123> |
Author | |
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options
Quote Reply
Topic: GT failed AirCare, need advice. Posted: 04 December 2008 at 11:03pm |
The O2 sensor is brand new, but yes, the injectors are possibly in need of a proper cleaning/rebuilding as this GT had been sitting for six years when I bought it.
|
|
Capt Fiero
Admin Group Founding Member Joined: 12 February 2007 Location: Canada Status: Offline Points: 4039 |
Post Options Quote Reply Posted: 04 December 2008 at 10:03pm |
By your readings, you are not running as rich as you were before, but HC are still high, if you have already replaced the O2 I would start thinking about getting a set of injectors rebuilt.
|
|
Capt Fiero
88 Fiero GT 5spd V6 Eight Fifty Seven GT V8 5spd. |
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 04 December 2008 at 9:11pm |
The good news... I passed AirCare !!!!!!!! The readings were relatively good... I went to the Surrey AirCare station today (Thursday afternoon) and was hoping they'd do the same as they did with Dave and NOT do the driving test due to Fieros being "too low" for the dyno as reported Here. However, they did the whole test and the GT passed easily enough. And keep in mind this was with NO cat. (Well, there is a cat on the car, but it's completely hollow!) The bad news... Even with the GT running just fine (supposedly) and passing the AirCare test no problem, the gas mileage is still absolutely pathetic - 14.36 MPG with my last fill up, and that's with me driving like an old lady. I've been taking it ever so easy on the gas. I'm even putting the car in neutral every time I slow down and stop so that the transmission isn't putting any drag on the engine while I'm sitting at a light. I may end up re-connecting the EGR and re-installing the stock PROM to see if that helps as this just isn't good enough.
|
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 20 November 2008 at 10:01pm |
Hey, no problem. I appreciate the fact you're trying to be helpful.
|
|
Capt Fiero
Admin Group Founding Member Joined: 12 February 2007 Location: Canada Status: Offline Points: 4039 |
Post Options Quote Reply Posted: 20 November 2008 at 9:58pm |
Sorry my bad, brain was in the wrong place. My Caddy Fiero has an intake air temp sensor, that is actually in the intake manifold. The Fiero sensor is on the air cleaner box. Sorry the last couple days have been way to long for me.
|
|
Capt Fiero
88 Fiero GT 5spd V6 Eight Fifty Seven GT V8 5spd. |
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 20 November 2008 at 9:43pm |
Dave, are you perhaps getting that confused with the MAT (Manifold Air Temperature) sensor? If so I believe my MAT is fine, as on a cold start it registers exactly the same ambient temperature as the coolant temperature sensor which feeds the ECM. The MAT then proceeds to show a higher reading as the temperature under the decklid increases. |
|
Capt Fiero
Admin Group Founding Member Joined: 12 February 2007 Location: Canada Status: Offline Points: 4039 |
Post Options Quote Reply Posted: 20 November 2008 at 7:38am |
Is the INT your Intake Air Temp sensor? Well if it is, a bad IAT sensor can cause poor gas mileage. As part of your fuel curve is based on the IAT sensor readings, it will add extra fuel based on how cold it thinks the air is. It could cost you 3-4mpg.
|
|
Capt Fiero
88 Fiero GT 5spd V6 Eight Fifty Seven GT V8 5spd. |
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 20 November 2008 at 1:44am |
Yeah, that's for sure. Thanks Chay, I appreciate your feedback. In This thread I reported that I'm only getting 15.5 mpg, mostly city driving. Is it reasonable to be expecting a lot better gas mileage than that if everything is performing as it should, especially considering I am NOT racing around?
|
|
CFoss
Senior Member Joined: 13 February 2007 Location: Canada Status: Offline Points: 580 |
Post Options Quote Reply Posted: 18 November 2008 at 3:12pm |
This is some black magic eh?
I read somewhere that the ecm has a 'learn' flag (Toggle, either on or off). The idea is that certain conditions have to be met, then 'learn' will turn on, and the int values will start to affect the blm numbers. I can't remember all the conditions, but two of them were that the car was running for a certain period of time, and the other was collant up to temp.
So, I have no idea what it is doing, but it's very likely that it's not affecting your fueling at this point, given that the collant is not up to temp. At the point referenced I believe a fule enrichment table would still be in play due to the reduced coolant temperature. An int (integrator?) is a short term value which will move the blm in time. I've read that the int will not affect fueling that much, but the blm will. There is a weighting algorithm something like the follwing: 100% fueling (duty cycle) = cell value (programmed in eprom)*80%+blm*15%+int*5% The idea is that the ecm will start off with the cell value as it's base, then get modified somewhat by the blm on a long term basis, then by the int a bit for short term changes.
Chay |
|
86 SE 3.4
|
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 18 November 2008 at 12:51am |
I got an informative PM from Chay (CFoss) regarding my WinALDL log. Much appreciated! I've copied it here so that others might gain from his knowledge.
Could any of you perhaps explain what's happening with the INT readings between 150 and 200. It demonstrates the same behavior elsewhere, but it's more noticeable there. What is actually going on when it peaks like that? Edited by Patrick |
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 17 November 2008 at 12:02am |
I’ve uploaded another WinALDL log Here which was taken last night on a short 10-15 minute drive back to my place (which means the engine wasn’t absolutely cold when the log began). Since my last log that I linked to earlier, I’ve unclogged the cat and the car goes a heck of a lot better! (I’ve also put the 180 degree thermostat back in, just in case anyone might wonder why the temperatures are different than last time.) Please download it and have a quick peek if you understand these numbers. My concern is that the engine might still be running a bit rich. I’d appreciate some feedback on this before I take another run through AirCare. Thanks.
|
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 09 November 2008 at 5:34pm |
Just want to add that last night was the first time since I unplugged the cat that I was able to take a decent run on the freeway (to the club meeting). Quite a difference in power! The biggest surprise was that club members in the parking lot thought the GT was "quiet" when I pulled up. ....
|
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 07 November 2008 at 1:07am |
I filled up my gas tank as soon as I drove the car so I could work out what kind of mileage I was getting while the cat was plugged. Are you ready for this... 9.4 miles per gallon. John, I hope it's considerably better now or I'll be needing this PROM redone. I will say that the GT feels a WHOLE lot healthier now. Sounds much better too! Edited by Patrick |
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 05 November 2008 at 11:03pm |
You bet. Yeah, I'm interested in learning what the numbers should look like when the engine is (hopefully) running normally.
|
|
CFoss
Senior Member Joined: 13 February 2007 Location: Canada Status: Offline Points: 580 |
Post Options Quote Reply Posted: 05 November 2008 at 10:52pm |
That's wicked good. Glad you found the smoking gun.
After running it for a while it'd be interesed in seeing another log file to see if the blms numbers get back to around 128. Chay |
|
86 SE 3.4
|
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 05 November 2008 at 10:23pm |
Here's the entire contents of my cat in the bottom of a bucket... I put the gutted cat back on and started her up... What a difference in sound! Didn't get a chance to drive the GT yet after getting the exhaust back together. However, judging from the sound, it should go a heck of a lot better. While I had the cat off, I took the opportunity to have a look at my front exhaust manifold from underneath. Well, I found the reason for the slight "tick, tick, tick" sound coming from it. The bottom bolt is broken off on #2 cylinder. That's a chore for another day (next spring). Next step is going through AirCare again. That'll probably be next week. Reports to follow. Edited by Patrick |
|
Matt
Senior Member Joined: 09 February 2008 Location: Canada Status: Offline Points: 448 |
Post Options Quote Reply Posted: 04 November 2008 at 8:12pm |
Good Lord that's horrid. I'm glad you finally got it all figured out.
|
|
I wanna go fast.
|
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 04 November 2008 at 7:27pm |
Pictures as promised... With all the symptoms I had observed (and with Chay's helpful comment about a possible "air blockage"), I suspected it was the muffler that was plugged (from the contents of the previous cat) because the current cat looked to be in such good shape from the outside. Here's the top:
Here's the bottom:
Here's the outlet: (A little difficult aiming the flash down 10 inches or so of pipe.) Notice how the "honeycomb" looks really good. Are you now ready for the money shots, two pictures (with slightly different lighting) of the inlet? Have a good look at why my GT was running so bad! Remember what I was saying earlier in this thread about a fine white dust?
Well guess what poured out of the outlet (through the intact honeycomb) when I tipped the cat on its end? Yep, you guessed it - a fine white dust! I wasn't hallucinating after all. I sincerely doubt that this very fine powder would plug the muffler. My fingers are crossed however that the previous cat didn't send chunks of its innards into the muffler. I think I lucked out as this appears to be the best-case scenario. I can probably beat the rest of the honeycomb out of this cat and then just put it back on. Won't even have to bother buying a straight pipe. Edited by Patrick |
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 04 November 2008 at 5:44pm |
Ah ha !!! Progress today. I got the cat off and it's plugged solid. Surveying this mess, I can't believe the motor could even run. Don't know for sure at this point if the muffler is affected or not, but looking at this current cat (it's not the original), I've got my fingers crossed that the muffler is okay. I'll post some pictures looking in both ends of the cat. It's quite interesting...
|
|
Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 04 November 2008 at 11:13am |
Okay, I understand. Thanks Chay. I found this image of the inside of a Fiero muffler. Looks like lots of places for debris to get stuck. Well, it's stopped raining. Guess I should crawl under the GT today to see if I can figure out what's going on.
|
|
Post Reply | Page 123> |
Tweet |
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |