Little bit of throttle sputter.
04-22-18, 08:45 PM
#1
Little bit of throttle sputter.
I dont know how to search this on the forums or i would have but i have a weird problem. I have a 93 FD3S i bought right before winter last year and didn't notice this problem or was oblivious to it, i only had time to drive it 3 times. It a fresh rebuild, good compression, street port, converted to single turbo, and has 2k secondaries (i believe) with the stock primaries, and an adaptronic CPU. The problem i am having is when i push the throttle in to just past where there is actual pressure on the pedal it dies for a good second then acts like nothing happend and revs just fine, unless im part throttle and am holding it at around 3k rpm where it bounces off 3k down to about 1k and then back up to 3k and so on. Im not sure whats going on CPU wise as i havent hooked up the laptop, but even then i wouldn't know, i have no idea what im looking at except the fact that the afrs need to be around 14:1ish. The sputter with the small amount of throttle is worse when the engine is cold, it just dies if i give it just a little bit of gas, which i figure is normal.
Today i decided to work the cob webs off and take it around the garage. It backed out fine and drove 50ish feet to where i stopped and then i tried to take off again and really had to give it some gas. When i stopped about 100 ft later, i had the clutch in and it was at sub 400 RPM. i thought i killed it, but it was still going, i gave it gas and it back fired pretty good. Then I let out the clutch to take off and it wasn't happy, sputtering and stuff until i got to about 2k rpms and it ran fine back to the garage but i kept the rpms up above 2k.
Im not sure if this is normal it doesnt feel like it should be doing this. But what could be wrong? I was thinking maybe the fuel pump is too weak or something or maybe the mismatched fuel injectors. Just asking for some ideas here.
Today i decided to work the cob webs off and take it around the garage. It backed out fine and drove 50ish feet to where i stopped and then i tried to take off again and really had to give it some gas. When i stopped about 100 ft later, i had the clutch in and it was at sub 400 RPM. i thought i killed it, but it was still going, i gave it gas and it back fired pretty good. Then I let out the clutch to take off and it wasn't happy, sputtering and stuff until i got to about 2k rpms and it ran fine back to the garage but i kept the rpms up above 2k.
Im not sure if this is normal it doesnt feel like it should be doing this. But what could be wrong? I was thinking maybe the fuel pump is too weak or something or maybe the mismatched fuel injectors. Just asking for some ideas here.
05-24-18, 12:13 PM
#2
Got my FD on a lift today to change out the driveshaft, got that all done and was gonna go drive it. It didn't want to start. I guess i ended up flooding it because i started it with the exhaust off and shut it off after about 1 minute. Got that straightened out and let it get to running temp, about 80C if I'm correct, and the idle dropped way off again like before. It was idling at about 480 rpm. It was running at like 13.5:1 to 14.8:1 when i have it set for running about 12.5:1, which i understand is okay for idle. I could give it gas and it would respond correctly to my input for a bit, then around 85C is dropped even lower about 350rpm to 380rpm and would start to back fire in the exhaust a bit when giving it gas. So i brought it back down to where it wanted to idle while i was looking at what the CPU was doing. The it died. Tried starting it and it was acting like it was flooded again and would start after a couple minutes of trying but it would idle right.
Before when I was trying to figure out if it was flooded I pulled the spark plugs to make sure they were okay, they were just overly wet. While i had different spark plugs out and in I listened to the compression. The compression sounds fine, since I don't currently have a tester this was the best i had, but it sounded like a healthy engine. I've worked on single piston 2 strokes and heard low compression from them and it sounded nothing like that (dont know if that matters but whatever). There's no way to honestly say its making perfect compression for a rotary. I'm just trying to figure out what could be wrong. I've added brand new gas and oil to the gas tank along with some octane boost to sort out the old gas. It ran fine after i added the gas last week but i never got it up to running temps. I let it get up to about 70C last week and figured that was enough to not flood it. But it still seems that its not getting enough fuel maybe? Maybe injectors? Fuel pump? I'm at a loss here, i could buy a new fuel pump and get new injectors but I'm not sure that would work. I might try to find a stock single turbo tune, or learn how to take it back. Maybe someone has seen this before and can give me some insight.
Just some background here: I would start it during the winter months about every 2 months and it would start and idle fine. I even got it to running temp, cant say for sure how hot but the stock temp gauge was sitting a little under half. I would red line it every now and again to keep the carbon deposits away. The last time it ran fine was middle of march. Nothing has changed between then and now, except an oil change, new drive shaft, and I added brake fluid since it was low and the clutch wouldn't engage. Other than that its exactly the same as when i put it away after driving it a few times before the snow after i bought it.
Before when I was trying to figure out if it was flooded I pulled the spark plugs to make sure they were okay, they were just overly wet. While i had different spark plugs out and in I listened to the compression. The compression sounds fine, since I don't currently have a tester this was the best i had, but it sounded like a healthy engine. I've worked on single piston 2 strokes and heard low compression from them and it sounded nothing like that (dont know if that matters but whatever). There's no way to honestly say its making perfect compression for a rotary. I'm just trying to figure out what could be wrong. I've added brand new gas and oil to the gas tank along with some octane boost to sort out the old gas. It ran fine after i added the gas last week but i never got it up to running temps. I let it get up to about 70C last week and figured that was enough to not flood it. But it still seems that its not getting enough fuel maybe? Maybe injectors? Fuel pump? I'm at a loss here, i could buy a new fuel pump and get new injectors but I'm not sure that would work. I might try to find a stock single turbo tune, or learn how to take it back. Maybe someone has seen this before and can give me some insight.
Just some background here: I would start it during the winter months about every 2 months and it would start and idle fine. I even got it to running temp, cant say for sure how hot but the stock temp gauge was sitting a little under half. I would red line it every now and again to keep the carbon deposits away. The last time it ran fine was middle of march. Nothing has changed between then and now, except an oil change, new drive shaft, and I added brake fluid since it was low and the clutch wouldn't engage. Other than that its exactly the same as when i put it away after driving it a few times before the snow after i bought it.
05-24-18, 08:03 PM
#3
Things that come to mind....
There's a boost sensor on a bracket affixed to the firewall just behind the throttlebody. It's labeled "Sensor boost" or some such. Check to make sure the connection is tight and that the vacuum hose is attached to it securely. The other end of that vac hose goes to a nipple on the right side of the intake manifold. Make sure it's secure at that end as well.
I'm not a tuner and don't know what type of single turbo you have, but the 2k injectors sound big and it sounds like it's flooding. One might be sticking or leaking.
I think fuel temperature sensors going bad can also give similar symptoms. Same with a throttle position sensor out of adjustment and intake air temp sensor that's bad.
What type of engine management do you have?
There's a boost sensor on a bracket affixed to the firewall just behind the throttlebody. It's labeled "Sensor boost" or some such. Check to make sure the connection is tight and that the vacuum hose is attached to it securely. The other end of that vac hose goes to a nipple on the right side of the intake manifold. Make sure it's secure at that end as well.
I'm not a tuner and don't know what type of single turbo you have, but the 2k injectors sound big and it sounds like it's flooding. One might be sticking or leaking.
I think fuel temperature sensors going bad can also give similar symptoms. Same with a throttle position sensor out of adjustment and intake air temp sensor that's bad.
What type of engine management do you have?
05-25-18, 07:56 AM
#4
Things that come to mind....
There's a boost sensor on a bracket affixed to the firewall just behind the throttlebody. It's labeled "Sensor boost" or some such. Check to make sure the connection is tight and that the vacuum hose is attached to it securely. The other end of that vac hose goes to a nipple on the right side of the intake manifold. Make sure it's secure at that end as well.
I'm not a tuner and don't know what type of single turbo you have, but the 2k injectors sound big and it sounds like it's flooding. One might be sticking or leaking.
I think fuel temperature sensors going bad can also give similar symptoms. Same with a throttle position sensor out of adjustment and intake air temp sensor that's bad.
What type of engine management do you have?
There's a boost sensor on a bracket affixed to the firewall just behind the throttlebody. It's labeled "Sensor boost" or some such. Check to make sure the connection is tight and that the vacuum hose is attached to it securely. The other end of that vac hose goes to a nipple on the right side of the intake manifold. Make sure it's secure at that end as well.
I'm not a tuner and don't know what type of single turbo you have, but the 2k injectors sound big and it sounds like it's flooding. One might be sticking or leaking.
I think fuel temperature sensors going bad can also give similar symptoms. Same with a throttle position sensor out of adjustment and intake air temp sensor that's bad.
What type of engine management do you have?
05-26-18, 02:43 PM
#5
Went out yesterday to see if I could find anything, the "boost sensor" vac line is connected and looks to be air tight. TPS seems about right I was watching it in the adaptronics control panel. Ill still have to look at the fuel temp sensor. But I did find one thing though, it seems I have a pretty large exhaust leak right after the turbo where its v-banded to the down pipe. So right before the O2 Sensor. I think I might be getting fresh air through that on idle causing my AFRs to go lean and my engine trying to compensate with fuel. And when I get on the gas it runs fine because its not sucking air through that leak but blowing out hot exhaust gases. I will have to see if i can repair the leak easily or have to replace the down pipe and see if this fixes the issues I've been having.
07-04-18, 11:35 AM
#6
Welp after going throught the car, kinda fixing the exhaust leak, making sure timing was on, pulling apart the intake and make sure that was all good.... I pulled the spark plugs and they were fouled. Put new ones in and it got rid of all my problems, but the now small exhaust leak.
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