*problem since i put my full exhaust on*

I've posted about this before but it's gotten worse in the past month. It used to be only in the morning and now it's a everytime thing...

When I first start the car it will idle up to 1500 and shoot back down to 500 and stall. Next start its a little better but once I get in reverse it bogs and sometimes its enough to stall. Then when I start driving the RPM's are unstable, the needle just bounces around where it should be. Then I get really bad throttle response.

Some days more often lately I'll throw a service light while im at about 35mph then when I come to a stop and it'll turn off. The code i've pulled in the past was a lean code. Because it's comming on while driving but not at idle im wondering if the EGR could be the problem.

The other night I went to show off for my friend at work and brake torque it and I couldn't even break the tire (lol peg leg) loose, I just bogged down. I think since putting my headers on I've lost more power than gained. To be honest since putting my headers on my cars ran worse and lost power. I know getting a chip burned could sove that problem but its sad that the stock chip cant handle the exhaust.

A mastertech at my work said to try a new TPS sensor and IAC but I figured if that was the problem it would of thrown a code ?

I dont even wanna drive my car anymore even though it sounds nice now lol

 

The stock tune can "handle" a full exhaust. At part throttle you would be surprised at what the BLM routine can compensate for. It's the cold start and WOT that will suffer the most. It sounds like you could be lean, the jumping tach leads me to believe a faulty control module as a dirty signal will cause this. If this does not fix the problem then it's most likely a dieing fuel pump. There should be no reason you should have the problems you are having just from the headers themselfs. Do you have a scanner where you work? Can you see what the BLM's are while under steady state cruise? This can tell us alot about whats going on. I would do the basics first and make sure you have fuel pressure, all the plug wires are connected, yada yada yada. I've tuned for hours on my friends car only to find something stupid wrong and have to start all over.

 

I would say check all the simple, stupid things you may have overlooked first. Did u happen to remove the distributor for any reason or mess with the timing, check to make sure your wires are all connected and are routed correctly and make sure your wires arent burnt anywhere, especially with a new set of headers. If you werent having these issues before you put your headers on, then most likely something got messed up during the install and you may have just overlooked it.

 

BMmonteSS, I had the ignition control module changed probably two years ago. I do have access to a scanner, I will try that tomorrow. I've checked the wires a few times and havnt found anything.camarorsssss, I havn't touched the distributor or timming. I too believe something got jacked up during the install but I just can't find anything.At the time of my previous post I was only having this problem in the morning and then when i went for my lunch break at work it was fine and the way home it was fine. Even though it still felt weak compared to what it was. Thats when I thought I was just having a problem with the computer in closed loop.I really appreciate the quick replys, I will fill you in tomorrow night if i dont get home too late.

 

I would get a a Lappy and WinALDL with ALDL cable connected to your test port. Get a data capture going from the cold start while recording all parameters. My guess is that NBO never reaches operating temperature - do you have single wire or three wire O2 sensor???

//RF

 

Update!

I was gonna take it to work yesterday but it acted up so much in just moving it from the parking spot that i quit on it. But i did take it today. Here's what I found from the scanner. Also note: the scanner read exhaust-lean the entire time.

IDLE
IAC = 59
TPS = .52v
BLM = 128

DRIVING
IAC = 128
TPS = 1.8v
BLM = 143

I've ruled out the wires being bad because the idle does stay steady and the RPMs are not always bouncing around. They're also fairly new and i check that they aren't arching or melted. I do want to check my fuel pressure though.

RF, I have a single wire O2 sensor.

I'd figure I should also fill peeps in that in my previous post I noted that I have been throwing codes 44 Lean and 53 AntiTheft.

ALSO lol I found something weird when I got back from driving it. I was in a parking spot and the MPH was still reading 50mph maybe it was something I did ? this is only my second time using it. THanks Guys!!

 

I see two distinct problems here. One is the fact that your BLMs while driving are 143. That indicates the system is too lean. You can think the increased intake flow due to the full exhaust for that. Idle BLMs are just about perfect. I would adjust the pressure to give more fuel at WOT and have the ECM pull fuel at idle/lower throttle. That will keep the system from running too lean, and give you backyour power.

http://72.19.213.157/files/TBI-AFPR.pdf

http://www.elmnet.net/~lange_c/c1500_washer_mod.html

Second, you have a 1 wire O2 sensor mounted in your header. I would recomeend a 3 wire with the built-in heater. This will ensure the O2 is at operating temperature at all times.

 

get a three wire NBO (AFS-74) ASAP. The reason why BLMs at idle are 128 is that NBO never gets up to operating temperature due to headers. ECM self bias 450 mV forces BLM to read 128. I bet that your integrator is also rock steady at 128. I had similar problem with my setup - I forgot to power-up heater circuit (did not install fuse in the fuse holder) as I was wondering why my BLM was 'always' at 128 at idle, while WBO was reading 13.2:1. Get a relay, in line fuse and run relay of IGN circuit. There is a write-up how to convert from single wire to a three wire somewhere in stickies.

//RF

 

My Van and GMC Jimmy have some un-used fuse slots in the fuse box. Next to them is a little place that a male style slot electrical connecter will plug in. I ran a pink wire from the spade terminal to the O2 sensor. Plugged the spade terminal into the slot in the fuse box. I used a 3 amp fuse in the fuse panel in that slot. I grounded the O2 sensor to the back of the driverside head. I bought the update harness from ebay. You basically plug the harness from the new o2 into the adapter harness. The purple signal wire goes to the standard 1 wire connector. Ground the black wire. The pink wire ran to the fuse box, keyed on power.

 

So my whole problem is my O2 sensor? I took it to work today to check the fuel pressure and thinking it was like my Truck which has a 4.3 TBI I thought it had a schrader valve on the fuel rail but i found out it didnt. The guy at my work had the connector that goes on the fuel filter but i said fudge that

 

Update!I think the reason my idle was at 128 Block Learn was because I was still in open loop. im still new at this stuff.I got a three wire and was ready to put it in and one of our master techs walked by and was like "WTF are you doin?". I explained the best I could but he said it wasnt gonna do anything. He started pokin around with his scanner and said that my Block Learn and Intergrator were good at idle but at high RPM that they got too far apart like 20-25 (At higher RPM I do throw the 44 Lean Code). He tried a different MAP sensor in it and it didnt really do anything but it did change the numbers a bit. When the car did get to closed loop i was getting like around 150 block learn not the solid 128 like i posted before. He did verify that the O2 was getting warm enough and it was doing what its supposed to. The other day it was reading lean the enitre time and when he used his it was jumping from lean to rich. He seemed more interested in if i am getting proper fuel volume and pressure, but he lent out his guage like an hour before I pulled mine in so he couldnt check it. I'm quite lost again.

 

Hmmm

How typical of the 'master' techs to dismiss a problem by just poking with a scanner. Get yourself a WinALDL and lappy so that you can learn what your engine is doing.

First of all in open loop O2 sensor is ignored and the engine can be managed to run at A/F ratios other than 14.7, usually richer or lower than 14.7. The ECM controls the fuel injectors without getting any feedback that the calculated fuel delivery rate actually matches what the engine received. A good example of open loop is when the engine is first started on a cold day. It requires a rich mixture to start a cold engine since a lot of the fuel doesn’t reach the combustion chamber. This is because a portion of the gasoline doesn’t vaporize and pools inside the manifold until engine heat vaporizes the fuel. Another reason that engines run in open loop when cold is that O2 sensors don’t work until they reach about 6008 F, so it takes a few minutes in cold weather for them to begin functioning. Open loop is sometimes used at idle conditions since some engines idle better with a rich mixture. In open loop, the ECM commands an A/F ratio that is determined from a table of A/F vs. engine coolant temperature. The open loop A/F is also adjusted to run richer as engine load increases.
In close loop ECM measures the A/F (air/fuel) ratio and uses this information to maintain the A/F ratio at a certain constant value. This mode uses feedback from an (oxygen) O2 sensor to close the loop. The A/F that the system tries to maintain is 14.7 to 1. The reason is that a 14.7 A/F ratio allows a catalytic converter to reduce exhaust emissions most efficiently. Engines don’t necessarily run the best at 14.7 at all times, but they produce the least emissions with a catalytic converter at this ratio. Also, it just so happens that the standard O2 sensor is most accurate at 14.7 A/F ratio, which gives a good feedback signal.

General comment (please do not take it the wrong way)

From your last post - it took a long time for ECM to enter closed loop since O2 was not hot enough. You have full length headers and if single wire O2 is at collector it is marginally warm enough to be operational. When NBO is cold it will report lean (low voltage) which amounts to BLM reading of 150 that your 'master' tech was seeing with his handy dandy scanner. Cast Iron exhaust manifolds retain heat much better than tube based headers.
Get a three wire NBO - it will make the whole system behave much better when cold. Why do you think every new car now days sports a heated sensor? To minimize amount of time ECM is operating in open loop.

Just my two cents worth - and please do not take it the wrong way.

//RF



https://www.thirdgen.org/open-loop-closed-loop

//RF

 

If I gave the impression that I have long tube headers I didn't mean to. I have the 68470 headers. Don't worry I don't offend easily lol. I'm begining to understand more about the open/closed operations but it used to only give me problems in the cold but now it even does it a little when it's warmed up.

 

So, I can see how a three wire O2 will get me to closed loop faster.. which will help but even in closed loop im still throwing a 44 Lean Code while driving 50mph

 

OK.
Sorry if I blew my stack a bit, not seeing the whole picture (car) makes it tough and interesting at the same time. Well, in this case Fast355 advise is appropriate. Just be aware when the car is doing 50 mph there is a lot air passing by your headers effectively cooling them down. Plus, once the car is up to speed it requires far less HP to maintain highway speeds. Under such conditions EGT's tend to drop and in combination with cooling air rushing by NBO may get cool enough, below 600F! Hence, heated NBO solves operating temperature problem by maintaining lambda element at near constant temperature over wide operating conditions. All things considered you'll get much better readings from a heated sensor.

//RF

 

A little update.. the car is officially undrivable. Lately its been taking longer and longer for it to start. I just got back from a simple drive to the bank but had to turn around because its worse than ever. I have to give it gas in very small increments. Too much gas at once and I get no response, like the gas pedal isnt even hooked up. That gets a little embarassing when your at a red light and it turns green and im stuck just coasting at 5mph trying to get up to speed. I really wanna take the advice of hooking it up to a laptop but I dont have access to one.

 

Time to check fuel pressure - what you have described above is a classic symptom of a dying pump or burst in tank hose. Rent fuel pressure gauge from autoparts store and measure fuel pressure before doing anything else.

//RF

 

!UPDATE! Turns out my fuel pump was putting out 13psi but didn't have the volume to hold it. So I broke down and had a guy at work put in a TPI fuel pump and new regulator. Wow, did it wake up the car. Thanks guys for the help. I hate when something takes a dump after you put something new on

 

dont disregard the suggestions made for the 3 wire sensor. cold weather is coming and you will find yourself with a not so good running beasty. also remember that e-10 sometimes is the culprit for lean codes and the large reason for the degradation of the small rubber line in the tank(not the only reason). you will find that the engine will on average run leaner, if you data log, with e-10. i would seriousl consider a full tune and the three wire upgrade. hopefully you also performed a voltage drop test on the new pump and corrected any electrical problems the fuel pump circuit had