Idle and throttle issues

blaxican27 · Aug 15, 2011

i am having very low idle at start up and throttle response is lagging. As soon as i go to crank the car it idles around 400 or so and stalls there then after a while it will idle fine. Even while driving, as i approach a stop or go to slow down and put the car in neutral, my idle will drop all the way down as if it is going to turn off. Sometimes it i will recover and idle fine and other times it stays down low. When it stays down low i try to give it throttle and it does nto respond. it takes it a few seconds stepping on the throttle to get it to respond. There are times where the car is running fine, then times were the idle drops really low, then times were it just shuts off. There is no consistant pattern as to what it does. I am currently running a 75mm TB, bigger plenum, hitech stage two cams, CAI. the car has been dynoed and tuned about 8 months ago. any suggestions or ideas?

Thanks.

SteedaGT9150 · Aug 15, 2011

clean your IAC and maf

darkside03gt · Aug 15, 2011

I would clean your maf and airfilter but also check your IAC valve and check for vacuum leaks. You can start the car and spray the connections with carb cleaner. If the idle raises then you have leak at that connection point. I would also check for air leaks after the MAF. The computer can correct for a certain percent of air loss after the MAF and if you are close to the max it can cause issues.

Green&GoldGT · Aug 15, 2011

I have the exact same problems, just not as bad as it used to be. I've had 2 dyno tunes. My tuner told me to replace my IAC, o2's, and IAT sensor with all Ford stuff, no help. New air and fuel filters, spark plugs, coil connectors, aluminum x-over PI, no help. Only thing I haven't perfected is TPS, which will be soon as I'm looking for a multimeter.

Temporary fixes I can suggest are opening the throttle body enough (using the throttle body stop) so it can idle with the IAC unplugged, and raising your idle by adjusting your parameters.

My car acts the same, sometimes it's fine and sometimes it acts up. I even had my tuner ride along and datalog the car. He got it to the point where it was virtually stall-less. I dropped him off, went on my way and the car stalled out on me about 20 times or whenever I pushed in the clutch and the rpm's went down.

Now does your car react by changes in humidity, like when it gets cold or rainy? Do you have any exhaust leaks? I'm going to try the carb spray soon.

blaxican27 · Aug 16, 2011

Green&GoldGT said:
I have the exact same problems, just not as bad as it used to be. I've had 2 dyno tunes. My tuner told me to replace my IAC, o2's, and IAT sensor with all Ford stuff, no help. New air and fuel filters, spark plugs, coil connectors, aluminum x-over PI, no help. Only thing I haven't perfected is TPS, which will be soon as I'm looking for a multimeter.

Temporary fixes I can suggest are opening the throttle body enough (using the throttle body stop) so it can idle with the IAC unplugged, and raising your idle by adjusting your parameters.

My car acts the same, sometimes it's fine and sometimes it acts up. I even had my tuner ride along and datalog the car. He got it to the point where it was virtually stall-less. I dropped him off, went on my way and the car stalled out on me about 20 times or whenever I pushed in the clutch and the rpm's went down.

Now does your car react by changes in humidity, like when it gets cold or rainy? Do you have any exhaust leaks? I'm going to try the carb spray soon.

I have not see it reacting differently in changes in weather. this problem just started about 4-5 days ago. My car is doing the same thing that as soon as i put the clutch in to go slow down RPM's shoot down and either stall real low or just turn on without even trying to recover. I will start off by checking my IAC and vaccuum leaks. MY IAC valve is under warranty so i may just replace it either way since its free as is.

blaxican27 · Aug 16, 2011

blaxican27 said:
i am having very low idle at start up and throttle response is lagging. As soon as i go to crank the car it idles around 400 or so and stalls there then after a while it will idle fine. Even while driving, as i approach a stop or go to slow down and put the car in neutral, my idle will drop all the way down as if it is going to turn off. Sometimes it i will recover and idle fine and other times it stays down low. When it stays down low i try to give it throttle and it does nto respond. it takes it a few seconds stepping on the throttle to get it to respond. There are times where the car is running fine, then times were the idle drops really low, then times were it just shuts off. There is no consistant pattern as to what it does. I am currently running a 75mm TB, bigger plenum, hitech stage two cams, CAI. the car has been dynoed and tuned about 8 months ago. any suggestions or ideas?

Thanks.

I used my tuner to pull codes and I ended up pulling up 4 codes...

P0171
P0174
P0720
P1000

Any suggestions or ideas?

trombonedemon · Aug 16, 2011

blaxican27 said:
I used my tuner to pull codes and I ended up pulling up 4 codes...

P0171
P0174
P0720
P1000

Any suggestions or ideas?

(P0171 System too lean bank 1
P0174 System too lean bank 2)-Clean your air filter and Mass air flow sensor, and make sure you don't have any vacuum leaks in the PVC system. Change fuel filter.

P0720 Output speed sensor Circuit Malfunction- find out which speed sensor malfunctioning

P1000 incomplete drive cycle- clear the first two and this code will go away.

03_TrueBlue_GT · Aug 16, 2011

Have you ever replaced your fuel filter?

trombonedemon · Aug 16, 2011

03_TrueBlue_GT said:
Have you ever replaced your fuel filter?

Quite a few times if you are asking me.

blaxican27 · Aug 17, 2011

Car is fixed and running like normal....i open my hood and to my surprise my CAI came apart at the middle coupling. my guess is the coupling got loose and ended up moving backward and so there wasnt enough holding up the front side of my intake and so it ended up falling out of the coupling which explains "too much air". I fixed the intake, cleared my codes, and reran my tune and its working perfectly. Thanks for all the help.

trombonedemon · Aug 17, 2011

blaxican27 said:
Car is fixed and running like normal....i open my hood and to my surprise my CAI came apart at the middle coupling. my guess is the coupling got loose and ended up moving backward and so there wasnt enough holding up the front side of my intake and so it ended up falling out of the coupling which explains "too much air". I fixed the intake, cleared my codes, and reran my tune and its working perfectly. Thanks for all the help.

What about the P0720?

sneaky98gt · Aug 17, 2011

blaxican27 said:
Car is fixed and running like normal....i open my hood and to my surprise my CAI came apart at the middle coupling. my guess is the coupling got loose and ended up moving backward and so there wasnt enough holding up the front side of my intake and so it ended up falling out of the coupling which explains "too much air". I fixed the intake, cleared my codes, and reran my tune and its working perfectly. Thanks for all the help.

Dude! I was reading through your first post, and I knew EXACTLY what your problem was! And it was this ^^.

A couple of years back, I was out in the middle of nowhere about 100 miles from home, and I had the SAME thing happened. Drove it for a while before it finally almost wouldn't run at all. Stopped, hopped out and popped the hood, and low and behold, the intake had fallen apart just after the MAF sensor. Naturally, I didn't even have a screwdriver to tighten the clamp back up on it. The solution:

Duct taped that bad boy back up and drove it on with no problems.

Glad to hear you got your problem fixed!

blaxican27 · Aug 18, 2011

trombonedemon said:
What about the P0720?

SES light has not come back on so i assume the P0720 fixed itself for the moment.

blaxican27 · Aug 18, 2011

sneaky98gt said:
Dude! I was reading through your first post, and I knew EXACTLY what your problem was! And it was this ^^.

A couple of years back, I was out in the middle of nowhere about 100 miles from home, and I had the SAME thing happened. Drove it for a while before it finally almost wouldn't run at all. Stopped, hopped out and popped the hood, and low and behold, the intake had fallen apart just after the MAF sensor. Naturally, I didn't even have a screwdriver to tighten the clamp back up on it. The solution:

Duct taped that bad boy back up and drove it on with no problems.

Glad to hear you got your problem fixed!

that is what you all custom ingenutiy....you do what you have to do with the resources available right...

trombonedemon · Aug 18, 2011

sneaky98gt said:
Dude! I was reading through your first post, and I knew EXACTLY what your problem was! And it was this ^^.

A couple of years back, I was out in the middle of nowhere about 100 miles from home, and I had the SAME thing happened. Drove it for a while before it finally almost wouldn't run at all. Stopped, hopped out and popped the hood, and low and behold, the intake had fallen apart just after the MAF sensor. Naturally, I didn't even have a screwdriver to tighten the clamp back up on it. The solution:

Duct taped that bad boy back up and drove it on with no problems.

Glad to hear you got your problem fixed!

Thus the reason I'm always keeping a flat-head screwdriver in my car, them rubber couplers are flemsy at best.

Crapped a brick the first time my Cold-Air intake fell apart on me while driving th car anic: .

Idle and throttle issues

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