1986 IROC with ZZ4 350

So I am starting a new thread, I replaced my Accel 30lb injectors with a set of Bosch3's 24lb injectors and what I am finding is that when the car goes into closed loop it get's really lean. 17-19:1.
It was doing the same thing with the 30lb injectors. I checked continuity from the O2 sensor connector to the computer and it was ok and I just replaced my 1 year old NGK O2 sensor with a Delco one and yet the same thing. I got all the little exhuast leaks fixed up as well, I made a copper gasket at work and used some aircraft grade gasket material. Worked like a charm:
Do you guys think the 24lb injectors are big enough for my set up?
350 ZZ4 with GM hot cam and TPIS miniram.
Any ideas why the O2 sensor is making it go lean???

I am running those exact injectors in my AMC 401. I'm running them at 45 psi and have plenty of fuel. I had to reduce my fuel tables down a good bit when I went to MPFI from TBI.

What is your exact combination besides the miniram? Specs on that hotcam? What heads and cr? What does the exhaust system consist of? Those injectors should be enough. Accel anything is pretty much garbage. Good to get rid of their injectors. What wideband are you using? Does the zz4 have the 58cc l98 aluminum heads on it?

LT4 hot cam: http://www.eecis.udel.edu/~davis/z28/buildup/cam/
10:1 compression, aluminum heads, ZZ4 crate motor:http://www.chevroletperformance.com/...9712&engCat=sb
hedman short headers with no cat and I'm using AEM AFR guage.
Fuel pressure set to 44 psi. Maybe I need it higher?

So any reason why on idle my WBO2 sensor keeps going max lean?
Could it possible be an ECM problem? The NBO2 sensor is brand new and continuity from the sensor to the computer is good?

Exhaust flow over the sensor. WB's dont do the greatest at idle.

peace
Hog

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Originally Posted by Hog

Exhaust flow over the sensor. WB's dont do the greatest at idle.

peace
Hog

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I have to disagree, when I burn a chip to stay in open loop the AFR is close to 14.7 on idle.

if it is staying 14.7 at idle where is it lean?

Sorry, my mistake. When I burn a chip to stay in open loop it stays near stoich near 14.7, as soon as it goes into closed loop when I enable it it then goes max lean.

Could the ECM have a problem?

I think what hog said is whats happening. most bins are 13.5 in open loop if your getting 14.7 even in open loop at idle your flow across the sensor is not enough to read 13.5 if that is what your bin is set at in open loop.

It kinda makes sense but it's not like it is going to 16 or 17 in closed loop, it gradually goes all the way and max's out the guage. Also, I can feel it hesitate when I give it some light throttle and run rought as opposed to when I burn a bin to stay in open loop so I don't think the gauge is lieing. Is there any other possibilities? I have a cousin with the exact same WBO2 sensor on his Subaru and he has no issues with a good reading on idle. I actually can't remember the exact number when I left it in open loop but I think was under 14.

it sounds like the afr is moving the same in open loop and closed loop idle like hog said lack of exhast flow, I don't know about the ecm that you have as far as adjusting the bin file, it sounds like the pump shot fuel increase is off , may be eagle mark or six shooter will be on here on a little while, they know about pump shots.

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Originally Posted by ZEDRATED

So I am starting a new thread, I replaced my Accel 30lb injectors with a set of Bosch3's 24lb injectors and what I am finding is that when the car goes into closed loop it get's really lean. 17-19:1.
It was doing the same thing with the 30lb injectors.

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Did you install the Injector Offsets that came with new injectors?

John at FIC said to just use the stock numbers and it wouldn't affect it much or And to just change the constant to 24.
I bought the injectors off him. He said he doesn't have correction for them and maybe they will be the same as ford's.
Also, is 43.5 psi enough? I think I would need a little more pressure???

The purpose of changing the injectors was to get one's with specifications for the bin file.

Still wouldn't explain why it is going max lean in closed loop but ok in open loop! And these are Bosch 3's. Should be the same voltage offsets as a ford 24lb injector. Never the less, shouldn't effect why it is going lean when in closed loop and idle but not in open loop??? I still say that somehow the O2 sensor isn't working properly for some reason.

OK, let's do it your way and start in the middle?

Not my way. That's what John at FIC told me.

So after us telling you what you need for 100's of posts over the last couple months you went and got more injectors without data just like the Accell and followed yet someones else's advice? The problem with Accell inectors, like Bosch, they are designed for Fords which don't need the data that GM ECM's do. But I believe the data is there for Bosch.

He took your money too right? Just like the dyno guy?

What have we charged you for all this advice to get going the correct direction? Maybe if you send us a big check you will listen?

zedrated, listen to eagle mark's advice an try what he says might work,you are running out of things to try from all your other sorces and like he said you haven't been charged a penny but it is taken peoples time trying to get you fixed. if you listen and try what he says might work you might be surprised how your vehicle preforms.[ hell with all the gauge set up do you want it to run or preform on a gauge ?]

zedradeted I don't have a wbo2set up,what I learned about tunning is get it to run reasonable, then if you have a lot of test equipment start seeing where ever thing is at.you are going after this backwards,wbo2 is a fine tunning tool if I understand this right. the posts I have read from a long time ago you should have listen to eagle mark and the other folks that had [sugestoins] then use your tools for fine tunning. eagle mark can fix it [if you do his suggestions]. like I said do you wont it to run or preform on a gauge or dino?

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Originally Posted by ZEDRATED

Still wouldn't explain why it is going max lean in closed loop but ok in open loop! And these are Bosch 3's. Should be the same voltage offsets as a ford 24lb injector. Never the less, shouldn't effect why it is going lean when in closed loop and idle but not in open loop??? I still say that somehow the O2 sensor isn't working properly for some reason.

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There's lots or reasons this could be happening with a modified motor and several adjustments to help with this situation. Or it may be the cam just needs to be OL Idle? What is your idle RPM set to? What is the MAP reading? Where is the O2 sensor located?

These are all things to look into and adjust after setting up the bin/calibration with proper information like Injector Batt Offsets.

So these are same as 24LB Ford injectors. Put them in a Ford and they will be just fine. But they are not the same as 24 lb GM injectors... so we need to insert proper Injector data! Or just go in ceircles again like we did with your 30lb Accell injectors.

What are the fuel trims saying when its goin lean? What are the o2 voltages doing when it goes lean? The wideband says its going lean so what are the trims and voltages saying when wideband says its lean?

Maybe I missed it but did you post a log for these guys to look at? Where is the wideband o2 installed at?

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Originally Posted by EagleMark

What is the MAP reading?

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I hate to be disrespectful but I come one here to learn and to listen and try things and maybe I have been a little stubborn at times but never disrespectful and always appreciative and you keep talking about me not listening and being very cocky on some of your replies yet you ask a question like this and by now u should know I have a MAF system!

You guys on here recommended me to John at FIC and said that he is a reputable guy, I also spoke to SouthBay and he couldn't give me voltage corrections either and John had told me that he couldn't give them and they are available if I look them up but said that it isn't a big deal on such an old computer so I kinda listened to him because talking to him he seemed like he really knew his stuff. Maybe the best thing for me to do is get an emulator and try things out on the fly.

I didn't post a bin for this problem yet, the WBO2 sensor is located just after the Y-pipe meets before the cat that is punched out. The NBO2 sensor is located on the left header just before the collector flange.

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Originally Posted by ZEDRATED

I hate to be disrespectful but I come one here to learn and to listen and try things and maybe I have been a little stubborn at times but never disrespectful and always appreciative and you keep talking about me not listening and being very cocky on some of your replies yet you ask a question like this and by now u should know I have a MAF system!

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Very rarely am I rude. But I thought it time to be blunt, we have hundreds of posts trying to help and this injector specs have been an issue since you started, long before you wanted to learn, when you were trying to hire someone to tune. Your right, I should have known it was MAF by now.

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Originally Posted by ZEDRATED

I didn't post a bin for this problem yet, the WBO2 sensor is located just after the Y-pipe meets before the cat that is punched out. The NBO2 sensor is located on the left header just before the collector flange.

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Not the bin, the XDL/datalog so we can see what is happening.

Narrow band is in header? Not collector or exhaust pipe? Do you have a picture?

If so your issue is common at idle with NB O2 sensor in header as it picks up one cylinder exhaust more then a blend do to low exhaust flow.

Here's a chart that shows the problem with injectors flow, they are not the same.

Attachment 5604

Also on another topic but it does have more charts with flow issues and how it effects tunes.

http://www.injectordynamics.com/WhosGettingDrilled.pdf

I just typed a long reply and it got deleted,not happy. thanks gearheadefi. Now Put the DAM wideband where it belongs. Stop trying to chase goofy injector data theories. Injector data is a small small part of your problem. Surprised these guys here haven't figured it out for you. This problem is not that complicated. Put the wideband in the PROPER location. Before a hollowed out cat is not the PROPER location. AGAIN what are the narrowband voltages telling you? If you knew how to read or post logged data you would see what the problem is. Good luck

never mind

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Originally Posted by ZEDRATED

So any reason why on idle my WBO2 sensor keeps going max lean?
Could it possible be an ECM problem? The NBO2 sensor is brand new and continuity from the sensor to the computer is good?

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Ok the narrowband is brand new, that's a relief. Now WHAT is it reading?? Who cares what the wideband is reading? Why are you hung up on the wideband reading?

http://www.gearhead-efi.com/Fuel-Inj...1&d=1380313658. This picture you posted of the narrowband in the header. PUT the wideband in the other header. Doesn't help that your narrowband is non heated I missed that part. Your problem is not injector data. Your narrowband does not like the overlap of the cam and being a cold sensor. It shows that when you put it in open loop it runs ok. That means your ve tables and injector data is close. When it goes to closed loop the narrowband goes crazy and the fueling goes downhill.

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Originally Posted by Hog

Exhaust flow over the sensor. WB's dont do the greatest at idle.

peace
Hog

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This was your answer. But actually the narrowband with a cam and non heated don't do well at idle and cause the wideband readings to go screwy.

zed rated try a heated o2 sensor, I put 1 in my old truck and it changed a lot, if it is heasetating it is more than likely transestion from idle to at lest half throttle [pump shot with a 7747 ecm] I don't know about the ecm bins in you vehicle try changing the injetor off set like eagle mark said.

What's with this idea that WBO2s don't work well at idle?

Using incorrect injector offsets can cause large problems especially at idle, so I would not recommend ignoring them...

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Originally Posted by Six_Shooter

What's with this idea that WBO2s don't work well at idle? Location and heat with his application.

Using incorrect injector offsets can cause large problems especially at idle, so I would not recommend ignoring them...

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People have tuned injectors with out all the data for years and have not had issues. Not saying its right or lookin to argue but imo its not his problem.

o/p your stock narrowband was designed to be used with stock exhaust manifolds and a cat. You have neither. Your narrowband is not heated. Neither type of 02 sensors narrow and wide work well with a cam with some overlap at idle with subobtimal conditions you are using them in. You have to help them work well. How does it run off idle and cruising and wot? Simple really why in open loop does it run different? The narrowband is going crazy, swinging up and down, overshooting. But in open loop there is no correction from the narrowband running off the ve table, which must be close. So how does injector offset data work in open loop and not closed loop?

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Originally Posted by S10LS

People have tuned injectors with out all the data for years and have not had issues. Not saying its right or lookin to argue but imo its not his problem.

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If you had been around for his other thread you would see what has been going on with this car, and in my fairly extensive experience in tuning MPFI systems the proper injector offsets are needed or at least offsets that are close.

I've tuned without them and once I swapped to proper offsets and then RE-TUNED for them the engines ran so much better than without.

So please stop posting this misleading information about how his O2 sensor was not designed for this or that, it is inaccurate and only serves to confuse the situation.

An O2 sensor was not designed to work in any specific situation or with other components, they are simply designed to create a voltage based on how much fuel is left in the exhaust that it happens to be sampling from. The only part I agree with is that the headers will cause an issue with a non heated O2, but is simply due to heat, and not because there are any other parts needed. Headers will simply move the O2 sensor away from the exhaust port which allows the exhaust to cool more than with manifolds and can cause the O2 sensor to stop working correctly, at which point if the ECM detects this it will drop out of closed loop.