Desperate for advice, race tomm (sun) and car wont rev past 5300 RPM's
06-04-2005, 10:08 PM
#1
Three Wheelin'
Thread Starter
UPDATE:Desperate for advice, race tomm (sun) and car wont rev past 5300 RPM's
Guys,
I need some help fast. I am racing at Autobahn with NASA this weekend. First 3 sessions and the race today found the car with what felt like hitting the rev limiter at 5300 RMP's. First lap or so would be fine then I could not get past 5300 without having the light on the AIM data unit go full xmas tree as if it was hitting the limiter. The shift light was not going off but it felt like a combo of starving for fuel or spark. The car would bog down and I could not get any power until I upshifted to the next gear. I raced 2 weeks ago and the car felt fine except the last 2 laps of the race when this started happening. The hesitation is so severe that it upsets the balance of the car in the middle of a turn. I did get about 5 laps today where the car ran fine and I was quick, then it acted up again.I am to race on Sunday but the way the car is acting, I am off the pace by 3.5 seconds on a 1.13 track (dead meat) I replaced the TPS last week thinking that might be the root of the problem but it is not. I spend a hour checking every line, hose and connection and did not find a problem. My battery is a little weak but once underway I am getting 13.5V per my data system. I also have a new O2 sensor. I would really like to race in the morning, does anyone have any idea of what to check. I am thinking it must be elect.
The rotor,cap,poiints, plugs and wires are less than a year old, fuel pump is the HD version and was replace over the winter along with the fuel filter. Engine was freshened up this winter as well. Clutch has 6 races on it.
PLEASE HELP THIS RACER BEAT UP ON SOME MUSTANGS,911's and MIATA'S. I have tools and am not afraid to use them!
The car is a 1991 944 S2 full race prep, mostly stock engine.
Thank you in advance for any advice you might offer!!
I need some help fast. I am racing at Autobahn with NASA this weekend. First 3 sessions and the race today found the car with what felt like hitting the rev limiter at 5300 RMP's. First lap or so would be fine then I could not get past 5300 without having the light on the AIM data unit go full xmas tree as if it was hitting the limiter. The shift light was not going off but it felt like a combo of starving for fuel or spark. The car would bog down and I could not get any power until I upshifted to the next gear. I raced 2 weeks ago and the car felt fine except the last 2 laps of the race when this started happening. The hesitation is so severe that it upsets the balance of the car in the middle of a turn. I did get about 5 laps today where the car ran fine and I was quick, then it acted up again.I am to race on Sunday but the way the car is acting, I am off the pace by 3.5 seconds on a 1.13 track (dead meat) I replaced the TPS last week thinking that might be the root of the problem but it is not. I spend a hour checking every line, hose and connection and did not find a problem. My battery is a little weak but once underway I am getting 13.5V per my data system. I also have a new O2 sensor. I would really like to race in the morning, does anyone have any idea of what to check. I am thinking it must be elect.
The rotor,cap,poiints, plugs and wires are less than a year old, fuel pump is the HD version and was replace over the winter along with the fuel filter. Engine was freshened up this winter as well. Clutch has 6 races on it.
PLEASE HELP THIS RACER BEAT UP ON SOME MUSTANGS,911's and MIATA'S. I have tools and am not afraid to use them!
The car is a 1991 944 S2 full race prep, mostly stock engine.
Thank you in advance for any advice you might offer!!
Last edited by Eric in Chicago; 06-30-2005 at 12:35 AM.
06-04-2005, 10:36 PM
#2
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Originally Posted by Eric in Chicago
PLEASE HELP THIS RACER BEAT UP ON SOME MUSTANGS,911's and MIATA'S!!
sorry...couldn't resist a pun.Anyway, donno what to say... DME relay? (that's JUST speculation)
06-04-2005, 10:48 PM
#3
Three Wheelin'
Thread Starter
Nope, DME is the new 993 part #. New last season. Nice pun. The Miatas are playing nice in this race, 2 weeks ago it was a different story, got punted off track by one that I was lapping...
06-04-2005, 10:50 PM
#4
Three Wheelin'
I assume the AIM is some sort of data logger or engine management system? Is the car leaning out when it feels like its tapping the rev limiter? How long has the gas been in the car? Bad batch? I know you said you just did the fuel pump and filter this winter but it might not hurt to do a volume test on the pump and change the filter out again. I assume it's dark over there now start the car up and put a heavy load on it, eg lights all on stereo on, AC on and see if your wires are arcing somewhere, possible bad wire? Does it idle normal and do everything else normal right up to 5300RPM? Vaccume leak? Just some random guesses and some stuff to check out, hope it helps some.
06-04-2005, 11:09 PM
#5
Three Wheelin'
Thread Starter
Azndrg,
The Aim is a data logger (throttle position, steering angle, lat G, RPM etc)
Not really feeling lean. Gas is 100 octane race fuel from a local gas station (in ground tank). I left the car at the track (50 miles away) and will go back to work on it in the morning. Stereo and AC are long gone. Idle is normal and all is good until 5300. Checked for vaccume hose being off or cracked, could not find anything. I am sure it is something simple and I am overlooking something, keep the ideas coming, there has to be something I am not thinking of.
Back to fuel, when I put 110 unleaded in for my qualifying session, I did not have the issue until the end of the session, It was mixed with maybe a 1/8 of a tank of 100 octane. The 110 came out of a drum. I would think fuel based on that, but my buddy running a 951 S filled up all his cans at the same station and he is not having a problem. I would not think fuel would cause a problem at 5300 every time. The engine is tuned to run on 100 or better and I have gone thru about 20+ gal. this weekend.
The Aim is a data logger (throttle position, steering angle, lat G, RPM etc)
Not really feeling lean. Gas is 100 octane race fuel from a local gas station (in ground tank). I left the car at the track (50 miles away) and will go back to work on it in the morning. Stereo and AC are long gone. Idle is normal and all is good until 5300. Checked for vaccume hose being off or cracked, could not find anything. I am sure it is something simple and I am overlooking something, keep the ideas coming, there has to be something I am not thinking of.
Back to fuel, when I put 110 unleaded in for my qualifying session, I did not have the issue until the end of the session, It was mixed with maybe a 1/8 of a tank of 100 octane. The 110 came out of a drum. I would think fuel based on that, but my buddy running a 951 S filled up all his cans at the same station and he is not having a problem. I would not think fuel would cause a problem at 5300 every time. The engine is tuned to run on 100 or better and I have gone thru about 20+ gal. this weekend.
06-05-2005, 02:44 AM
#6
Bad news, I am betting you have a broken valve spring. Cutting out at 5300 rpm is a classic symptom. The good news is that its a relatively easy fix, the bad news is that you won't be racing tomorrow. Get it fixed before you drop something in a cylinder and really hate life.
Regards,
Regards,
06-05-2005, 05:51 AM
#7
Rennlist Member
Not to contradict Scott, but have you checked basic things like FPR and damper? How about the ignition control module? Ever been replaced?
WHAT IS IT WITH THESE S2 HESITATION PROBLEMS!
WHAT IS IT WITH THESE S2 HESITATION PROBLEMS!
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06-07-2005, 11:25 AM
#8
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Luis -
Didn't you just replace the TPS? Did that solve your hesitation problems?
Semi-Off Topic - Sorry - How hard is it to replace the TPS on our S2's??
Didn't you just replace the TPS? Did that solve your hesitation problems?
Semi-Off Topic - Sorry - How hard is it to replace the TPS on our S2's??
Last edited by AndyK; 06-07-2005 at 11:50 AM.
06-07-2005, 03:12 PM
#9
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Originally Posted by Eric in Chicago
PLEASE HELP THIS RACER BEAT UP ON SOME MUSTANGS, 911's and MIATA'S.
Sorry the ole' killer bee was out of action (btw, I love those graphics). You were really tearing it up, there, for a while. Hopefully you'll be good to go for Gingerman!
06-07-2005, 03:36 PM
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Have you checked the spark plugs? I ran into this once where the car drove fine and smooth until 3000 rpms and then it was like it hit a brick wall and would not gain any rpms. I pulled the plugs and replaced with fresh ones, ran like a top after that.
06-07-2005, 03:39 PM
#11
Instructor
What's the latest on this Eric? If you had raced Sunday we could have duked it out to see who had the crappier motor! Losing power just sucks. Can't believe that it happened to three of us in one weekend. I'm getting a BMW.
So what's the idea behind running 110 octane in your car? Is that so your chip can work better? Or do you have a very high compression motor and worried about pinging?
Sorry about losing you on Sunday, we missed you during the race. Hopefully we'll see you strong as an ox at the next one.
Cheers,
Tristan
So what's the idea behind running 110 octane in your car? Is that so your chip can work better? Or do you have a very high compression motor and worried about pinging?
Sorry about losing you on Sunday, we missed you during the race. Hopefully we'll see you strong as an ox at the next one.
Cheers,
Tristan
06-07-2005, 04:22 PM
#13
Three Wheelin'
Thread Starter
Thanks for the replies guys (What the hell are the 911 boys doing on this forum???)
I did not run the car on Sunday as did not want to make it worse, in case it was a valve spring. My feeling is that it may be something in the MAF, the door may be getting stuck and not letting the engine breath. After looking at my data, the engine did get above 5300 rpms a few times and when it did the laps were fast. The plugs are only 1 race old, the cap and wires are fresh as well. I trailered the car to the shop and will wait to see what the outcome is.
BTW, the TPS is very easy to replace on a S2. 2 phillips head screws holding it in, takes all of 4 min. to change. Dont have to take anything off to get to it.
As for mr. deceiver question, The 110 was compliments of Eurosport, they had some left over gas from the GrandAm race and I thought it might help my problem. No chip or compression bump, nice 10:1 ratio. PCA would not like to see a stock engine with chips or higher compression. When our cars are on, it will be some great racing between the 3 of us!!
Mr. Bagadonuts, thanks for the compliment. I will be ready for Gman, I have to make up a lot of ground on you and your stranglehold of 1st place in the Midwest points chase!!! Hell, I might have to go to the race in Iowa just to make some up on you!!!
As I am leaving for Le Mans in the next couple of days, I wont be able to report back until after the 22nd. I will make sure to post the results.
I did not run the car on Sunday as did not want to make it worse, in case it was a valve spring. My feeling is that it may be something in the MAF, the door may be getting stuck and not letting the engine breath. After looking at my data, the engine did get above 5300 rpms a few times and when it did the laps were fast. The plugs are only 1 race old, the cap and wires are fresh as well. I trailered the car to the shop and will wait to see what the outcome is.
BTW, the TPS is very easy to replace on a S2. 2 phillips head screws holding it in, takes all of 4 min. to change. Dont have to take anything off to get to it.
As for mr. deceiver question, The 110 was compliments of Eurosport, they had some left over gas from the GrandAm race and I thought it might help my problem. No chip or compression bump, nice 10:1 ratio. PCA would not like to see a stock engine with chips or higher compression. When our cars are on, it will be some great racing between the 3 of us!!
Mr. Bagadonuts, thanks for the compliment. I will be ready for Gman, I have to make up a lot of ground on you and your stranglehold of 1st place in the Midwest points chase!!! Hell, I might have to go to the race in Iowa just to make some up on you!!!
As I am leaving for Le Mans in the next couple of days, I wont be able to report back until after the 22nd. I will make sure to post the results.
06-07-2005, 04:34 PM
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Eric,
I too am anxious to hear your findings. Although I have a NA 944 SPEC car, I was (past tense) having the EXACT symptoms you are. I tried coil, rotor, wires, DME fuel relay and cleaned the AFM and those did not help. I did replace the plugs and it (knocking wood) worked great for the last weekend in Phoenix with POC. I did purchase a DME/brain just in case, but have not installed it yet. They are good to have around. The problem was intermitant (generally at the beginning of a session and under load). It later became a constant problem and my lap times showed it.
I too am anxious to hear your findings. Although I have a NA 944 SPEC car, I was (past tense) having the EXACT symptoms you are. I tried coil, rotor, wires, DME fuel relay and cleaned the AFM and those did not help. I did replace the plugs and it (knocking wood) worked great for the last weekend in Phoenix with POC. I did purchase a DME/brain just in case, but have not installed it yet. They are good to have around. The problem was intermitant (generally at the beginning of a session and under load). It later became a constant problem and my lap times showed it.
06-07-2005, 04:57 PM
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I had a problem simular to this a while ago... once it started building boost it would cut out, sometimes like a rev limiter, sometimes a bit more violent then this. Checked and replaced a bunch of things. I finally gave the COIL a look... there was some green corrosion on its connection, so i replaced it (and the wire to the distributor) and it fixed it.
Check the coil, and if its old, replace it anyway (doubt its old on your car)
This is what I put in, found cheaper locally:
http://www.lindseyracing.com/Merchan...y_Code=944COIL
~Eyal
Check the coil, and if its old, replace it anyway (doubt its old on your car)
This is what I put in, found cheaper locally:
http://www.lindseyracing.com/Merchan...y_Code=944COIL
~Eyal