strider681

alright my initial problem was I failed emissions a bunch of times and my car ran like crap. I removed my fuel pump pulsator and replaced it with submersible fuel line to avoid the thing leaking every year. I thought the low fuel pressure and it not holding when pump shut off was causing the 160 BLM and high INT. I tried plugging off all vacuum lines coming off intake including pcv and power brake booster with almost no difference. oh I also replaced my CAT and muffler because they were clogged. my car runs alot better now, but still the high BLM and INT. at idle the BLM is 160 and INT is usually steady at 128. at P/T both values go to 128 but O2 sensor goes to 4mv extreme lean. i have replaced the O2 sensor twice now. I am going to do a full compression test asap and will post results. only non stock replacements are the air intake is a "cold air" setup still using the MAF (attached pic). I did buy a programmer and try the 6E code, which it runs alot better but still the same problem with the INT and BLM. I realize any of my gaskets could be leaking and after i do a compression test I'll know alot more, just thought I'd throw this up in case anyone has had the same problem.

1987 Pontiac Firebird Trans Am V8 350 5.7L FI 700R4 Auto Transmission

irocuroc

just for fun see if you have a blown fuse on one of the injector banks. They run on 4 injectors and will be way lean if you do

strider681

thanks for suggestion but I did one up from that and made sure each injector connector was recieving power, and also tried unplugging each one at a time and they all affected idle. to do that I made a little test probe from a small dash light and made sure it lit the light. I also sent all the injectors out for cleaning and flow testing a few months ago. I am pretty certain at this point the issue is no longer fuel, especially because I removed the vac line going to my FPR and plugged it on the intake side giving me 43 PSI at all times and it still adds fuel. I also wanted to point out that my PCV valve rattles alot at idle even tho i have replaced it like 3 times now.

Viprklr

iTrader: (5)

Do you have any exhaust leaks before the O2? Any oxygen that gets added to the exhuast stream ahead of the O2 sensor will skew the readings. The ECM will compensate for the incorrect info.

strider681

i don't have any exhaust leaks beofre the O2 that I can tell, but I suppose maybe my exhaust manifold is leaking? if my compression test comes out good that'll be something i'll do is remove the manifold and replace the gasket. one thing I did notice is the EGR doesn't open when I apply vacuum, but the old one i have opens fine with vacuum applied. maybe I got the worng one last time (positive type instead of negative). anybody seen the wrong EGR or defective one cause 160 BLM at idle tho?

irocuroc

IS THAT WHEN THE PROBLEM STARTED. THE EGR IN YOUR CAR SHOULD ONLY OPEN WHEN VAC IS APPLIES. AIR COMING IN WILL RAISE THE BLM

strider681

well when I had the intake plenum off getting the injectors serviced, the car did the same thing before and after. but if i remember correctly, I put back on the same EGR which even looks little different than the old one i got, the old one is pretty open on the bottom and you can push up on the diaphram. the new one is mostly closed on the bottom with only small holes that you can't really even push up on the diaphram thru. it's just kind of a pita to remove the intake plenum, and the gaskests are not cheap enough to replace alot. but really I am wondering if just having a 'P' type EGR versus a 'N' type would cause this. thanks for your input!!

Edit: I found the reciept and the EGR I bought last time is the part# for the wrong one. I'm surprised it ran ok as long as it has, I am going to replace it with the Negative back pressure valve asap.

strider681

well I tore off the intake plenum, put back on my old Negative pressure EGR after making sure it worked, pulled the fuel rail and replaced all the o-rings and the fuel pressure regulator diaphragm/spring assy. I also put on a crane AFPR to make sure I could set my base pressure to the high end of the 41-47 spec. problem of 160 BLM is still there.. I don't hear any apparent vacuum leaks, none that would make the BLM go to 160 in cell 0. my manifold vacuum is pretty steady at 20 hg so that say no manifold vacuum leaks right? one thing is my pcv valve "trips out" at idle it rattles all crazy and i've replaced a few times and the grommet and made sure it was the right one. so I unplugged the hose comming off the throttle body and going to passenger valve cover, hooked a gauge to the cover side and got 2.5 hg at idle and didn't change at p/t. on the port comming off the throttle body there was no vacuum at all.. closed or p/t. is that normal? can someone check that? maybe the gasket under that "tuned port injection" plate is shot? the other one is the distributor base to manifold gasket could do this too?

Edit: also I tried unplugging each injector one by one again and they all just made the engine stumble kinda weird except #7 made the valve start clacking all crazy, which it already makes a little noise "normally" so idk maybe the valve is all weird and since it's right next to the O2 sensor its driving it crazy. but now my O2 sensor reads kinda normal still more lean but stays like 3-600 mvolt range. one of the studs on the passenger side exhaust manifold is busted off so the connection isn't very tight, but would a slight leak here cause the 160 BLM?? INT goes to 128 and neither value changed very much when i squeezed the hose from PCV valve to intake but RPM did drop.

strider681

alright went at it again all day today and still no luck. I changed the distributor base to intake manifold gasket, replaced my A.I.R. hoses and one of the check valves. since it was still doin same thing I put it up on ramps and jacked the passenger side exhaust up to make the connection there tight (missing a stud) and still same problem. performed a compression check and all cylinders read 148-152 engine warm except #2. this sucker went to 180. anyone know what causes that? and since 2 is opposite 7 on the firing order, and #7 is the one with the noisy vlave that gets worse when fuel injector is unplugged, could that be my problem? when I was doing the compression test I noticed 2 of my exhaust manifold bolts were loose, so I went around and tightened them all and most were loose, thought for sure that would do it and BLM only went to 134 for a few min then i revved it a few times and something happened like something warmed up and took a dump cuz then the BLM shot to 152. thing is too my IAC was reading higher counts meaning it was using more vacuum leak to make idle. then when the BLM drop do did IAC down to like 10-15. guess next step is to pull valve covers and check out my valve lash. the car is def running lean, when i pulled out the spark plugs they all had this black mark on the insulator and tips where tan/white. book says overheating, basically running lean causes that. I did try setting my injecotr constant in the PROM from 22.36 to 24lb/hr. that should give it more fuel right? well didn't really change much. basically after the valve covers and lash and trying my old air box I'm pretty much out of ideas and will prob have to take it in to a shop bummer

Viprklr

iTrader: (5)

That'll lean it out more. The ECM thinks it has larger injectors so it'll hold them open for a shorter amount of time.

strider681

alright got an update on this problem.. I finally removed my valve covers and adjusted my valve lash. a couple of the rockers were more loose than others, and I found a bent push rod on #2 intake valve. I also replaced my exhaust manifold gaskets, they were def shot and I think I used RTV on them last time my valve cover gaskets didn't look pretty either and i def used RTV on these last time. also made sure each plug was getting a spark with one of those testers (just a light bulb basically). after replacing the push rod on #2 intake it doesn't go 180 compression like before anymore, goes to 155 like the rest. engine sounds awesome now. i can hear my alternator over my engine at idle. but even tho it's running better than i ever remember, my scan tool still shows the BLM go to 150 at idle. one thing i tried was i bought caps and put them on the A.I.R. tubes where the check valves go. this made my BLM only go up to 140. does anyone seal the connections where the A.I.R. tubes hook into the exhaust manifold? next i started pulling injector plugs again, on the driver side they all made INT shoot up real quick to 145 before i could plug it back in. but on passenger side they didn't seem to make as much of an impact, and it took longer. i think one or two even made the INT go down to 118? so i rechecked and made sure each injector plug had voltage and "pulsed" on my light bulb test. they all were good. i'm kind of getting stumped and think maybe i got a crack in the block or something.. the car runs great like i said makes good power now but it always compensates all that fuel once the O2 starts reading the exhaust. oh yeah i tried running it with MAF sensor unplugged for grins, and did same thing. the only obvious kind of leaking sound I hear is the PCV valve and hose, i know cuz when i pinch the hose it goes away. oh yeah i replaced the hose and PCV valve for the hundredth time and it quit rattling.. but it still does kinda make some noise like a leaking air sound but goes away when i pinch the hose. makes INT start creeping up when i do that. oh and I replaced my exhaust manifold stud while i had it off so my exhaust is all sealed good at the engine, but i had the air tube coming off the CAT not plugged.. does that let air into the exhaust that can affect the O2?? i need to get the pipe back on it, broke while i was doing valve covers JB weld didn't hold lol so yeah anybody got a clue, idea, or even wacked out suggestion? thanks in advance

strider681

ok I finally got the ***** and interest to dive into the MAF Scalars and Tables to fine tune my BLM's and thought I'd share how I went about it so maybe someone else will understand it better I read alot of info in articles and threads and stickys and none of them really said what to do very well IMO so here is my attempt:

First I used AUJL as base bin as stated before because it's listed as 2.77 rear axle gear ratio and my original ABWW is as well. I failed emissions twice in the last few months and realized that AUJL has alot less timing than ARAP or ABWW so I copied anything spark related from ARAP (this might make a difference if you have different timing than ARAP basically 20-40 SA versus 16-30 SA in AUJL) the only mods I was tuning for were that I have an open air element or "cold air intake" with k&N filter and I grinded off the little walls in the plenum behind the throttle body.

Instead of messing with Injector constant, I left it at 22.36 and instead changed MAF Table Scalar 1 from 16 to 19. this brought cell 0 and 1 down to about 135-140. When I set the scalar to 20 it ran super rich BLM & INT both went to 108. I then set the Scalars for table 2 & 3 up 3 points each to mimic table 1. Table scalar 4 went up 2 points and I left scalars 5 & 6 alone. Then I started paying close attention to what cell I was in at what airflow, that's basically the key. it's really hard to do with auto xray, but data master has an awesome feature called histogram. this thing shows what cells you hit and what the high, low and average BLM are . So I was still apprehensive about messing with the table values, but decided to just make minor changes and see what happens. with all said and done I made most of the changes to tables 1 and 2 and only changed tables 3 and 4 first entry to the last of the previous. Tables below show original AUJL and my modified values.

MAF Table 1 Scalar
16 19

MAF Table 1
6.02 7.71
3.35 4.30
4.38 5.66
5.93 7.71
7.99 10.45
10.40 13.38
13.41 16.21
17.02 20.41
21.40 24.90

MAF Table 2 Scalar
30 33

MAF Table 2
21.38 24.90
24.00 26.50
26.63 29.68
29.63 33.67
32.63 37.45
36.00 41.64
39.56 44.63
42.94 49.01
46.69 50.80

MAF Table 3 Scalar
53 56

MAF Table 4 Scalar
86 88

so as you can see besides the first few values in table 1 for idle, it's pretty much a 3-4 point offset that worked for me. I made percentage based increases in first 6, then 3, then 1 percent increases until it was so close to 128 or went under too much. my biggest problem was cell 2 was rich when others were lean, and cell 5 and 6 went rich on me too at a certain point so it was a little difficult to see exactly where they are but pretty much end of table 1 and beginning of table 2 is what i adjusted to bring it in. now all my BLM are 126-132 and that is good enough for me! well for now to go pass emissions hope this helps