check engine light stays on, lean condition...help?

[blkvenm97]

I just got my mach 1 about 2 months ago and I got a real good deal on the car just tryin to work a few minor bugs out. the check engine light was on when I got it and it had idling up issues and so forth. I had it checked at the parts store and it was throwing 2 codes. One for a bad tps sensor and one for bad maf sensor. I've since replaced both of those and it's doing alot better than it was but the check engine light is still on (I unhooked the battery to take it off and it was off for about an hour of driving and doing fine then came back on). I had it checked again now it's throwing a code for a lean condition but doesn't say why it has a lean condition. I knew it was lean because of the smell of the exhaust...you can just tell. it will idle high when I come to a stop in neutral until a rev it a little then it falls to normal idle. every now and then it seems it wants to stall out but not often. I read in the new mm&ff mag where someone in an 02 gt had a problem that sounds identical and they told him to check the vacum hoses and air intake hoses for cracks or loose connections. I did this but can't seem to find anything wrong with any of those. this isn't a major problem but it is a problem nontheless that I do not want. I'm sure it's hurtin performance some which is a no-no and I do believce it's robbing some gas milage. any help would be greatly appreciated! thanks guys
Michael

 

[SvTDsG]

If the car is not tuned, I see that you have a superchips hand held that may not be enough to get the ecm to read the MAF and see what it wants, it will cause this problem, also if the MAF sensor is clocked the wrong way can cause this, like you said about vacuum hoses check them with the car running while lightly spraying some carb/brake clean over the hoses and intake tube even manifold itself, take the shaker off to help with checking the manifold. Any air leak past the MAF will set a lean mixture code. When I had my Mach I had a similar issue you are having after installing my JLT intake, while driving the car no matter how cruising or making a pull push the clutch in and the rpms went below 1500 it would just cut off. Got a tune and it fixed it! Hope this helps you. I don't check this section often anymore since I got my cobra. So if you want to ask me any questions PM me.

 

[blkvenm97]

I just sprayed some carb cleaner on my intake and hoses and couldn't find any problems there. I'll check the maf sensor but I'm pretty sure it's on there right as far as I know. I don't know what else it could be other than maybe it needs a tune but I've never saw this model do anything like that over installing the minor bolt ons I have. I know the 05 ups have picky ecus and usually need a tune even after just an air intake install but does this model also have that issue? my 97 cobra had minor bolt ons similar to this and it never did anything like that. Not sure what it is but I hope to get to the bottom of it soon, thanks!

 

[Socal Mach]

The issue with the hanging RPM's is likely in your sig, you have the BBK twin 65mm throttle body, check the TPS voltage.

 

[blkvenm97]

The issue with the hanging RPM's is likely in your sig, you have the BBK twin 65mm throttle body, check the TPS voltage.

that's what i've been told but I've since put the stock throttle body back on but it hasn't fixed the issue. it burns lean cuz you can smell it and on start up it'll puff a lil white smoke out. every time the car is in neutral or when the clutch is pressed in (at a stop or between gears) the reved will climb some...you can give it a lil rev and it comes right back down to normal. i'd really like to find out how to get the check engine light to go off and the problem to be fixed. somehow the problem seems to be connected but I can't be sure. it was way worse before I fixed the tps sensor and maf sensor but I'm still having this issue. any help would be appreciated greatly. when I get the cash I plan on getting a dyno tune and maybe that will work the bugs out but I'm hoping to find the issue before that if possible. thanks guys

 

[bigtrain72]

try and get some crc maf cleaner and spray the maf to clean it and get some crc qd electronic parts cleaner to clean connectors in the maf and tps then try some dielectric grease on both maf and tps connector if that dont work u need a new maf

also what is the tps voltage if its above 1.0v it will make rpms climb at idle

 

[blkvenm97]

I'm not sure what the voltage is how exactly is it that you check that? I'll try that other stuff too...I already put a brand new tps and maf sensor on it but I guess it's possible they were dirty somehow or just no good to begin with...thanks

 

[4valvemach]

What does a lean exhaust smell like?

What do the plugs look like?

Whats the fuel pressure at?

Have you cleaned the throttle body and IAC valve yet?

Whats the mileage of the Mach?

 

[bigtrain72]

I'm not sure what the voltage is how exactly is it that you check that? I'll try that other stuff too...I already put a brand new tps and maf sensor on it but I guess it's possible they were dirty somehow or just no good to begin with...thanks

use a multimeter probe the middle wire on the tps and set it to 20 on dc current and should tell u the voltage of the tps normal range is .96-.98v steady when key on and car running

 

[blkvenm97]

What does a lean exhaust smell like?

What do the plugs look like?

Whats the fuel pressure at?

Have you cleaned the throttle body and IAC valve yet?

Whats the mileage of the Mach?

havn't checked the plugs as it doesn't really seem like an issue that would concern the plugs but it's possible I guess. fuel pressure has not been modified and I havn't checked it but I assume it's at the stock setting. I have not cleaned the IAC valve or throttle body I guess I could try that. I havn't actually checked the milage as in a mpg test but I've owned several mustangs and I'm familiar with the milage their supposed to get in near stock form and this one just doesn't seem to be getting it. seems like it uses more fuel than it should...I will do a test soon but I'm almost 100% it's using more fuel that it should. with mixed drivin mostly on backgrounds and in town I may be able to pull 200 miles or so out of a tank...seems a lil low to me. it has stock 3.55 gears. I might be able to squeeze out more milage than that but I know not a whole lot more than that. I should be getting high teens around town easily if not slightly higher than that. that's what I've always pulled before and most other ppl say that same. I'll check up on these things and try to see what's up. thanks guys!
Michael

 

[blkvenm97]

I meant to say mixed driving mostly on backroads...not backgrounds my bad lol...been a long day

 

[blkvenm97]

What does a lean exhaust smell like?

What do the plugs look like?

Whats the fuel pressure at?

Have you cleaned the throttle body and IAC valve yet?

Whats the mileage of the Mach?

as for what a lean exhaust smells like..well that's kind of hard to explain. of had cars that were lean before and one had turndowns so it was bad...when you ride around with turndowns it's bad enough as it is with your clothes and things smelling like exhaust but even worse when you're lean or rich...as it has a stronger smell...hard to explain

 

[Socal Mach]

Check for exhaust or intake leaks. It could be as simple as the gasket for the throttle body being on backwards.

 

[blkvenm97]

never thought about that I'll check it out bro thanks

 

[jk_aktion]

does the dtc indicate which bank is lean if not both?
what octane is currently being used?
does the vehicle lag/hesitate at wot?

check for a vacuum leak, a vacuum leak will cause a lean condition. car not running - unplug the fuel pressure sensor vacuum line, grab someone who smokes and have them blow cig smoke continuously through the vacuum lines and look for leaks.

faulty fuel pump, fuel pressure driver module can cause lean condition. fail do to age/overworked and not enough power supply. battery/alternator.

check the spark plugs, post a pic of them.

a "misfire" will cause a lean-misfire or rich-misfire determined by a/f ratio with spark. btw a misfire doesn't just have to be "a no spark". engine wear: carbon build-up, and low compression can cause this as well. i'll explain more if needed in depth.

start with plugs and vacuum leak, i'll help you diagnose.

 

[blkvenm97]

does the dtc indicate which bank is lean if not both?
what octane is currently being used?
does the vehicle lag/hesitate at wot?

check for a vacuum leak, a vacuum leak will cause a lean condition. car not running - unplug the fuel pressure sensor vacuum line, grab someone who smokes and have them blow cig smoke continuously through the vacuum lines and look for leaks.

faulty fuel pump, fuel pressure driver module can cause lean condition. fail do to age/overworked and not enough power supply. battery/alternator.

check the spark plugs, post a pic of them.

a "misfire" will cause a lean-misfire or rich-misfire determined by a/f ratio with spark. btw a misfire doesn't just have to be "a no spark". engine wear: carbon build-up, and low compression can cause this as well. i'll explain more if needed in depth.

start with plugs and vacuum leak, i'll help you diagnose.

doesn't usually have any problems with lagging or anything like that at WOT...I did get on it pretty good one day and ran to redline in 2nd gear and let off of it and put it in neutral because I was comin to a quick stop and the rpms did fall and the car died...that's the only time anything like that has happened as far as wot. it just said it had a lean condition. the dtc didn't specify any more than that. I havn't checked the spark plugs but I will. A couple people have told me to try that. I did check for vacuum leaks using carb cleaner while the car was running and couldn't find any leaks that way. thanks

 

[blkvenm97]

ok I'm getting closer to getting this issue fixed. the lean problem is fixed...one of the 02 sensors had a tear in the little white wire going to it so I replaced it and fixed the issue and milage has majorly improved. the check engine light did come back on now it's throwing a code for 02 sensor slow response...anyone know what could be causing that other than just a bad 02? I think it could be caused by the 02s being blackened by the car running lean for a while. is it possible they could be cleaned to fix the issue or would i have to just get new 02s? as for the lagging throttle I think the tps voltage may be too high. someone said anything over a 1.0v could cause this as I had it checked one day it read 1.01 or something like that. If this is the issue how exactly do you set it down some? someone at a shop told me the tps could be sticking as it's not throwing a code for bad tps but when the revs hang you can tap on the tps with a screwdriver and it falls back to normal every time. if this is the case is there any way to get it to "unstick" or would I just need to return it and get another one? it has at least a 1 year warranty on it so it can be replaced...hell it was only 30 bucks anyways so if I have to I'll pay another 30 bucks if it fixes the issue. got her 80% fixed now fellas...on the home stretch. I also recently purchased an sct xcal 3 with a bama tune and it helped the car some too. thanks for the help guys!

 

[blkvenm97]

oh another thing guys...these bbk throttle bodies are known to be touchy...somewhat sensitive. I don't have an issue with the throttle hanging because of my tbody as the issue is unchanged between the stock and bbk...my question is why is the damn thing so much stiffer? is there any way you can modify this and run the bbk and have it feel more like stock? I'd like to run it but was wondering if there's a way to fix the stiff throttle feel once it's on...thanks!