powerpigz-51

Hey guys.... I have a 85 with a 4+3, and the 870 ECM. Since my rebuild, I have had issues with "top end" performance. It seems to hit a wall about 3900 rpms, and will only rev to about 4300. Keep in mind that I am running Ford yellowtops, which are a 19 lb injector. (I did not know better at the time) I have a AFPR set at 45 pounds, which is about as low as it will go. Last summer I bought all the chip burning and scanning stuff from Moates. When I replaced the chip with one that I had burned, it turned out to be a ADS super chip. I used a stock 1F bin that I got off the net (probably for an auto), did a global change on the injector constant and it runs better than the ADS chip, but the wall is still there. I left it like that until now, as I want to play around some more. I guess where I suck the most is figuring out the scans, as I have only done a few. Is there a question in here somewhere? Yes, lots! I would like to post a scan, but do not know how (tunerpro rt). What I have noticed is that in 4th with the hammer down, the BLM's are at 148,( this was the same with the ads chip) the o2 voltage is at 888 mv. At cruise, (closed loop) everything is normal. This tells me I am dead lean, correct? I also noticed the Maf grams top out at about 105 gps....should it not be more? Maybe with more RPM's? I have taped the gauge to the windshield and all seems normal. Also on the scans, my MPH is way off. Top speed is 51 mph and i think I hit 85 one time. What the hell am I looking for on the scans? I am thinking fuel restriction, and supposedly my injectors are good for 300 plus HP. My engine is basically stock, screenlees Maf, no cat, ported plenum. Help!

bjankuski

You need to find out why it won't rev it may not be the computer. The 888 MV at WOT is not lean, (anything above 450 MV is richer then 14.7 AFR). Without seeing the car I would guess you have some sort of exhaust restriction like clogged CATS that is restricting the flow. That is why it will not rev and that is why the MAS only reads 105 gps, fix the restriction and it will rev.

powerpigz-51

Thanks Brian....you were the one that showed me how to change the injector pulse about a year ago, thanks! I am sure I have some sort of restriction. The MAF flow was a red flag to me on the scans, and the MAF vs. RPM table is telling me that I am getting about half the max flow I should be getting. The one cat I have is completely gutted, and my muffs are resonator tips, so exhaust restriction is unlikely. I see I am backwards on the o2 voltage, but why are my BLM's at 148 when my o2 is saying it's pig rich? (this is at WOT). Closed loop everything seems fine. Is there something else in the scan to look at to give me a clue? Is there a way to check the MAF to see if it is defective? Thanks again! And what about the MPH on my scans....what could be causing the diff between real speed and scan mph? Also....is the 02 sensor in play at WOT?

powerpigz-51

Riddle me this........after looking at my scan, I noticed that my car does not go into open loop at WOT (4.65v on the throttle position sensor). It went from open to closed at warmup, but nowhere during my scan did it go back into open loop. This is a snapshot of the scan when I was putting the wood to it:
27mph vehicle speed
3550 RPM
4.65v TPS
159f coolant temp (does not seem right.....says about 185 in cockpit)
100f MAT
98.3 gms/sec Maf
5.91ms injector
145 BLM
128 INT
888mv o2
85 crosses 02
142 Load v
closed loop
I think this was a first gear stab on the on ramp....keep in mind that the pins are jumped during a scan on my car.

rodj

For want of a better explanation ;
once in CL ,the ECM does not go back into OL when in PE (WOT ) mode
The fueling in PE is the "same" as in OL ;in that it is direct from the tables and does not take the O2 sensor readings into account , but the ECM is still in CL mode until engine is turned off or the 02 sensor drops out from being too cold