HOW TO DO AN ADVANCED SEARCH.
Mon Jul 08, 2013 3:56 pm by Admin
For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.
When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).
After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …
Comments: 0
Similar topics
Latest topics
Log in
my backfiring problem...
+8
Dawgz83948
944-LT1
948
stu wright
Wild Bill
Porch
Admin
v8944
12 posters
Page 2 of 3
Page 2 of 3 • 1, 2, 3
Re: my backfiring problem...
sounds like a plan, i think i'm going to try the chandler motorsports cap and rotor since they have a 1 year warranty on it, and nick chandler said he's never had one come back, so that sounds good to me. do you have any links for cleaning the opti? i've found a little about it, but nothing great...looks like i just need to pull it apart (carefully) and shoot some isopropyl alcohol on it (not on the sensor though right?) let it dry out, then reassemble?
v8944- Posts : 211
Join date : 2009-06-09
Age : 33
Location : Bowie, MD
Re: my backfiring problem...
Yes, you need to inspect and clean the optical sensor and the transmissive disk. If it is only dusted with dirt I would use cotton swabs dipped in alcohol......
948- Moderator
- Posts : 573
Join date : 2009-06-09
Age : 109
Location : East PA
Re: my backfiring problem...
pulled the old opti off last night...epic, catastrophic rotor failure....chunks and slivers of plastic EVERYWHERE inside the cap...glad i picked up that used one from robbie!
v8944- Posts : 211
Join date : 2009-06-09
Age : 33
Location : Bowie, MD
Re: my backfiring problem...
PICTURES!
_________________
[You must be registered and logged in to see this image.]
[You must be registered and logged in to see this link.]
944-LT1- Moderator
- Posts : 1265
Join date : 2009-06-09
Age : 102
Location : NOTRE DAME
Re: my backfiring problem...
WhAA!!!
And it ran like that? Wow.
And it ran like that? Wow.
_________________
[You must be registered and logged in to see this image.]
[You must be registered and logged in to see this link.]
944-LT1- Moderator
- Posts : 1265
Join date : 2009-06-09
Age : 102
Location : NOTRE DAME
Re: my backfiring problem...
DAYUM! Holy Opticrap Batman....
xschop- Posts : 2711
Join date : 2009-06-09
Location : OKC
Re: my backfiring problem...
more like it stopped running like that lol
v8944- Posts : 211
Join date : 2009-06-09
Age : 33
Location : Bowie, MD
Re: my backfiring problem...
Doesnt quite explain the blue smoke though.
_________________
[You must be registered and logged in to see this image.]
[You must be registered and logged in to see this link.]
944-LT1- Moderator
- Posts : 1265
Join date : 2009-06-09
Age : 102
Location : NOTRE DAME
Re: my backfiring problem...
well, the smoke may have only appeared blue because of the camera...if you listen to the video one more time, toward the end when i was revving the engine, you will be able to hear a nasty miss, where the engine actually bogs. i believe i had a missfire the whole time, and that was causing a lot of the smoke. I also pulled the intake manifold yesterday, and discovered a lot of oil where oil should not be, so i think some of my problem may have come from oil leaking past the intake manifold gaskets and getting sucked into the cylinders...possibility?
v8944- Posts : 211
Join date : 2009-06-09
Age : 33
Location : Bowie, MD
948- Moderator
- Posts : 573
Join date : 2009-06-09
Age : 109
Location : East PA
Re: my backfiring problem...
just wanted to follow up on this. I pulled the motor and completely resealed it (minus the headgaskets) and installed a gm opti with a new cap and rotor, and this opti i sealed around the outside at the joints with black rtv. I also painted the engine bay in the process, satin black. The results: the backfire is 99 percent gone, it no longer backfires when i release the accelerator, and then push on it again. The one thing i haven't fixed yet is my "tip in" problem with my BBK 58mm throttle body. I'm pretty sure the damn thing is just too big, and the car hasn't had a proper tune yet, so it bogs a bit if i push the accelerator too fast...like it's trying to trick me, then the revs come up hard.
I've read that it's probably the computer sending a super lean signal when the throttle blades are moved too quickly (not even to wide open). If anyone locally has LT1 tuning software, i'll buy you a case of beer! I've learned to live with it for now, i might try fiddling (with a voltmeter) with the TPS to see if it's just a little too far closed (idle dips low every once in a while), which might contribute to my problem...and i'll check 02's just in case
ps, threw in a couple of pictures from the recent snow!
[You must be registered and logged in to see this image.]
I've read that it's probably the computer sending a super lean signal when the throttle blades are moved too quickly (not even to wide open). If anyone locally has LT1 tuning software, i'll buy you a case of beer! I've learned to live with it for now, i might try fiddling (with a voltmeter) with the TPS to see if it's just a little too far closed (idle dips low every once in a while), which might contribute to my problem...and i'll check 02's just in case
ps, threw in a couple of pictures from the recent snow!
[You must be registered and logged in to see this image.]
v8944- Posts : 211
Join date : 2009-06-09
Age : 33
Location : Bowie, MD
Re: my backfiring problem...
Thats a good lookin engine. I've always thought the LT's looked better than the LS.
laptop_geek- Posts : 230
Join date : 2010-05-14
Age : 33
Location : Memphis, TN
Re: my backfiring problem...
Do you have a VSS? Not having one can contribute to odd engine behaviour around idle and tip-in...
948- Moderator
- Posts : 573
Join date : 2009-06-09
Age : 109
Location : East PA
Re: my backfiring problem...
huh...never thought about that. I don't have one...do you really think it could cause this much of a noticeable problem?
v8944- Posts : 211
Join date : 2009-06-09
Age : 33
Location : Bowie, MD
Re: my backfiring problem...
bluehellfire666 wrote:huh...never thought about that. I don't have one...do you really think it could cause this much of a noticeable problem?
In my case not having the VSS has caused idle issues, stalling when coming to a stop or going to neutral when moving, and some driveability issues from a standstill.
One could suppose that a larger TB, no tune, and the lack of a VSS could combine to cause this issue.
A quick search...
[You must be registered and logged in to see this link.]
Also, have you checked for intake leaks??
948- Moderator
- Posts : 573
Join date : 2009-06-09
Age : 109
Location : East PA
Re: my backfiring problem...
i just completely resealed the whole motor, and went over the intake system for leaks with a pretty fine toothed comb. I'll take a look around tomorrow to see if i can spot anything blatantly obvious, but the way that it runs i don't think i have any vacuum problems. I don't have any problems with going to neutral or clutch in, or stopping with the idle...drops right back to where it's supposed to be 99.9 percent of the time. Occasionally it will idle a little bit low, but often corrects itself or i start moving again before it has a chance to correct itself.
It also does this odd thing when it goes from closed loop to open loop (or whatever way it goes when the computer starts using the O2's). If i let it warm up, which i do almost always, it will try to lower the idle a little bit, and will go too low, then the computer will compensate and rev up to about 1500 rpm, then the idle will drop to maybe 500 or so (way low) and then rev up again...but it'll never stall. It'll cycle like this a few times then the idle will settle in very nicely and the car will run beautifully, except for that damned hesitation.
Important fact, the hesitation isn't just from idle, if i hold the throttle at 2000 rpm, and open it quickly it will bog and hesitate hard...not a lack of spark hesitate, i know what that feels like. It will do this at almost every rpm at almost every time.
It also does this odd thing when it goes from closed loop to open loop (or whatever way it goes when the computer starts using the O2's). If i let it warm up, which i do almost always, it will try to lower the idle a little bit, and will go too low, then the computer will compensate and rev up to about 1500 rpm, then the idle will drop to maybe 500 or so (way low) and then rev up again...but it'll never stall. It'll cycle like this a few times then the idle will settle in very nicely and the car will run beautifully, except for that damned hesitation.
Important fact, the hesitation isn't just from idle, if i hold the throttle at 2000 rpm, and open it quickly it will bog and hesitate hard...not a lack of spark hesitate, i know what that feels like. It will do this at almost every rpm at almost every time.
v8944- Posts : 211
Join date : 2009-06-09
Age : 33
Location : Bowie, MD
Re: my backfiring problem...
Go get it tuned! Or put a stock TB back on it and see what happens, I bet your Issues will go away.
Re: my backfiring problem...
okay, just ran out and swapped out the throttle body for a stocker...didn't fix it, but it seemed to have helped with my powerband. If i nail the throttle above (an estimated) 3000-3500 rpm, no hesitation and no miss and she goes like stink. If i blip or nail the throttle below those rpm's the engine tries to stall and seems to miss, then picks up, but not super quick. If i accelerate smoothly, but still very quickly, i will occasionally feel, but often not hear, a little bit of a miss of some sort (kind of a little bump in the core of the car). If I accelerate smoothly but not quite as quickly, up to WOT, no misses, no hiccups, just hard pulling to the moon.
List of recent parts:
Used GM Opti, thoroughly cleaned with alcohol and sealed up with a new cap and rotor
New MSD plug wires separated using plug wire holders every 6-8 inches to prevent ANY arching
New Ignition Coil
New Ignition Control Module
New Spark Plugs, gap checked on all ~6-8 months ago (very few miles on them, just lots of time)
New Coolant Temp Sensor
New intake seals all around, no vacuum leaks as far as i can tell
Less than one year old O2 sensors
Got a fresh PCM and had it mail order tuned, properly this time with No emissions.
Running a LS1 MAF
Could intake tubing size be part of my problem? Right now i have 4 inch tubing...it is larger than the MAF, but the MAF is in front of all of the tubing, so there shouldn't be any problems right?
edit: just had a thought...could i be collapsing a lifter? They're the stockers.
List of recent parts:
Used GM Opti, thoroughly cleaned with alcohol and sealed up with a new cap and rotor
New MSD plug wires separated using plug wire holders every 6-8 inches to prevent ANY arching
New Ignition Coil
New Ignition Control Module
New Spark Plugs, gap checked on all ~6-8 months ago (very few miles on them, just lots of time)
New Coolant Temp Sensor
New intake seals all around, no vacuum leaks as far as i can tell
Less than one year old O2 sensors
Got a fresh PCM and had it mail order tuned, properly this time with No emissions.
Running a LS1 MAF
Could intake tubing size be part of my problem? Right now i have 4 inch tubing...it is larger than the MAF, but the MAF is in front of all of the tubing, so there shouldn't be any problems right?
edit: just had a thought...could i be collapsing a lifter? They're the stockers.
v8944- Posts : 211
Join date : 2009-06-09
Age : 33
Location : Bowie, MD
Re: my backfiring problem...
What push rods are you using?
Could be push rod flex if they are stockers.
What injectors are you using?
If they are stock you may have one that is shorting internally, or could be dirty.
GET A TUNER ON IT! They can look at everything and see what is going on.
Could be push rod flex if they are stockers.
What injectors are you using?
If they are stock you may have one that is shorting internally, or could be dirty.
GET A TUNER ON IT! They can look at everything and see what is going on.
Re: my backfiring problem...
push rods and injectors are both stock.
When you say get a tuner on it, do you mean do a dyno tune day? or should i invest in a LT1 tuning software? I'm super short on cash right now (i'll show you my bank account balance to bring that point home), i guess that is the life of a college student...i think i need a part time job!
I'd personally really like to get tuning software and tinker with it for a while to see if i could figure everything out. Something like LT1 edit or the likes...it's too bad i didn't go LS back in the day, i could've had a lot easier time with all this crap!
When you say get a tuner on it, do you mean do a dyno tune day? or should i invest in a LT1 tuning software? I'm super short on cash right now (i'll show you my bank account balance to bring that point home), i guess that is the life of a college student...i think i need a part time job!
I'd personally really like to get tuning software and tinker with it for a while to see if i could figure everything out. Something like LT1 edit or the likes...it's too bad i didn't go LS back in the day, i could've had a lot easier time with all this crap!
v8944- Posts : 211
Join date : 2009-06-09
Age : 33
Location : Bowie, MD
Re: my backfiring problem...
Is it better or worse as the ambient temps change? In other words is the problem more noticeable when it's hot outside? Does it get better when it's cold? It sounds like a tip in enrichment problem. If it was a carburated engine it would be discribed as the accelerator pump function. It sounds like you're not getting enough gas on throttle tip in. The leaness will cause popping. Download a free copy of Datamaster and do some data logging. It will show up. It's tuneable.
sbwrench- Posts : 66
Join date : 2009-06-09
Re: my backfiring problem...
Take it to a professional tuner, Don't try it yourself unless you plan to spend some money on parts! There is a reason professionals get paid what they do. One minor blip in a map,which there are quite a few that the motor uses, can screw up parts fast! With a situation like yours , it's not a newbie tuner fix. Save your money, don't drive it unless you have an AR gauge, and get it fixed. If you are running lean, reason for the AR gauge, you will screw some stuff up
Re: my backfiring problem...
Megasquirt 3? Cheaper than a stock opti and you can have all kinds more fun.
adam7e- Posts : 63
Join date : 2010-03-11
Re: my backfiring problem...
Sorry, but a little Hyjacking here,,,,,,
Adam7e, How much of a pain was it to install the megasquirt? Is it user friendly? Did you eleminate the opti and go with something different? If so can you start a tread about it/your bulid?
Adam7e, How much of a pain was it to install the megasquirt? Is it user friendly? Did you eleminate the opti and go with something different? If so can you start a tread about it/your bulid?
Page 2 of 3 • 1, 2, 3
Page 2 of 3
Permissions in this forum:
You cannot reply to topics in this forum
Today at 3:06 pm by Rob44
» LEAKING TPC HYDROBOOST
Wed May 01, 2024 8:32 am by Rob44
» Fesler Saratoga Top
Tue Apr 30, 2024 8:28 am by JW1970
» Parts availability for general maintenance?
Mon Apr 29, 2024 10:36 pm by zenon
» What coilover spring rates are you running with torsion bar removed?
Mon Apr 29, 2024 10:24 pm by zenon
» 944 Turbo TPC Radiator Install Help Needed
Sun Apr 28, 2024 9:38 am by SpeedRacer11
» HYDRAULIC THROWOUT/RELEASE BEARING NOT ENGAGING FULLY
Sun Apr 28, 2024 12:00 am by Raymond-P
» Best engine uprights/plates
Sat Apr 27, 2024 11:09 pm by Raymond-P
» Rear coilover suspension setup
Fri Apr 26, 2024 3:30 pm by ThomasJoseph315
» Ray's 1987 944 LS1 Build & Swap
Mon Apr 15, 2024 6:59 pm by JW1970