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Re: 86 tpi bogs and stumbles after driving when hot
Getting into PE depends on throttle position and LV8 for MAF cars I believe. For MAP cars like mine it's throttle position and manifold preasure.
Note that PE is not the same as open loop. During PE, the ECM technically still remains in closed loop (Just that it's not paying attention to the O2 sensor while the BLM Learn is disabled). The tables for open loop and PE are different.
On a stock car, if your BLMs are good during closed loop operation, there wouldn't be any reason to expect your AFRs are wrong during PE. Unless there are one or more injectors that are malfunctioning and/or not flowing enough to keep up with demand of WOT, or your fuel pressure is falling off. But I think you've navigated past those issues already.
Re: 86 tpi bogs and stumbles after driving when hot
Originally Posted by ULTM8Z
Note that PE is not the same as open loop. During PE, the ECM technically still remains in closed loop (Just that it's not paying attention to the O2 sensor while the BLM Learn is disabled). The tables for open loop and PE are different.
Okay that makes sense, I was wondering why my log was showing "closed loop" under WOT from the other day
Re: 86 tpi bogs and stumbles after driving when hot
I drove the car a bit this evening but was not able to datalog this time. I am not sure if there has been any improvement or if the car was not running long enough to give the same symptoms. Once it warmed up, at WOT I had much less spitting/sputtering when the RPMs stopped climbing but it was maxing out at 3500 RPM and still felt sluggish getting to that point.
Re: 86 tpi bogs and stumbles after driving when hot
Unfortunately I don't have an adjustable FPR. Would the lean running cause my issue even though it is mostly after the car is warmed up and running a while?
If this snap shot is during PE, it's odd that the integrator is even reacting.
I sent you a couple logs from this evening. The chip is on a 6E mask, car is a 305 auto.
Any help on this would be great, car is starting to drive me nuts lol
Only thing I can see in the log I have where I am at WOT (4V TPS) the O2 sensor is reading extremely low the entire time, at one point less than 100. I was under the impression that the lower reading is lean however shouldnt the sensor be seeing a rich mixture under WOT?
Last edited by 2012sergen11; 09-26-2017 at 06:50 PM.
Re: 86 tpi bogs and stumbles after driving when hot
Looking in the .bin file that I have that should be burned on the chip I am running the scalar for FI size is 19.48 lbs/hr. Do we usually need to lower this for the Bosch III's so they do not run too lean? I thought I read on the site here usually around 17 lbs/hr.
Like I said still very new to this (datalogging/tuning) but enjoy learning
Re: 86 tpi bogs and stumbles after driving when hot
I know this isn't your part number southbay would be able to state the flow.
Originally Posted by southbay08
well this is good news!
Just to add my two cents, the 710's are rate at 20lb on the net...however once again, it depends on what calibration fluid they use. . The 710's flow closer to 21.7lb at 43.5psi but in all honesty the engine will not know the difference between 20 and 21.7lb. I'm sure you know that they actually flow 19lb but it's important to know that it's at Ford pressure which is around 39psi
Re: 86 tpi bogs and stumbles after driving when hot
After seeing the low o2 readings it definitely seems like a fuel issue so I am going to check fuel pressure tomorrow once the car is hot and see what kind of pressure I have at WOT. If the pressure is all good then I would have to assume the lean condition is caused by the tune / injectors relationship
Re: 86 tpi bogs and stumbles after driving when hot
Originally Posted by 2012sergen11
Looking in the .bin file that I have that should be burned on the chip I am running the scalar for FI size is 19.48 lbs/hr. Do we usually need to lower this for the Bosch III's so they do not run too lean? I thought I read on the site here usually around 17 lbs/hr.
Like I said still very new to this (datalogging/tuning) but enjoy learning
I have some datalogs from you from back in June of this year? What injectors were you running back then? What injector constant?
I want to compare the injector pulse widths for similar RPM and load condition vs BLMs and integrator. Also at WOT pulse widths.
Re: 86 tpi bogs and stumbles after driving when hot
The logs you have from June would either be those "start and stall" or just after I installed the Bosch IIIs. The car never actually ran with the Multecs that were in it.
Re: 86 tpi bogs and stumbles after driving when hot
The chip with the adjusted offsets for the Bosch injectors was installed at the time i installed the injectors. Went from stock 86 prom to the 6e mask prom.
Re: 86 tpi bogs and stumbles after driving when hot
The one hint I'm getting that you're going lean in WOT, is in your 3rd log and what's happening in closed loop.
At time = about 10 seconds, you start to get into the throttle (but not quite all the way to WOT). I see the rpms start to climb and by the time you get to 3300 rpm, the Integrator is pegged lean at 160. My guess is that when you're in WOT at that same rpm, you're so lean the engine simply running out of fuel and can't climb any higher in the RPM range.
If you haven't messed with your VE tables or your PE tables, then it's probably true you have to adjust your injector constant down a little. Try going down to 17 and see what happens. That seemed to be the magic number on my friend's '91 305 TPI when he put on Bosch-III 19 lb/hr injectors.
Re: 86 tpi bogs and stumbles after driving when hot
I'll post up results later of the fuel pressure I get. Maybe the pump is heating up and causing an issue because it is on its way out? The pump is very loud back there...
Re: 86 tpi bogs and stumbles after driving when hot
Originally Posted by 2012sergen11
Well got some bad news...fuel pressure at idle in park was 38 psi, still in park opened throttle up around 75% and pressure dropped to nearly 15 psi
Well, before blaming the pump, just make sure the filter isn't clogged. After that, make sure your pressure regulator is good (not bleeding off too much pressure back to the fuel tank). Then check to make sure you're getting full system voltage to the pump (i.e, +12V supply wire is good and the ground is good). If those all check out, then yeah, probably the pump is bad.
Either way, you've found at least part of your lean-out problem. Get all of that resolved first, and then we can look at the new data again to see what tuning mods are needed (if any).
Re: 86 tpi bogs and stumbles after driving when hot
Yea I am hoping it is not the pump. The pump is pretty loud in the car but I don't feel like dropping the tank (and I'm not cutting the floor).
I'm planning to see how quick the pressure bleeds off. Also going to check the filter. If both those turn out okay I'll look at the voltage. In tunerpro there is a "voltage to fuel pump" variable but is that accurate at all?
Re: 86 tpi bogs and stumbles after driving when hot
I think that's only looking at the +12V switched ignition voltage (I'm not even sure it's an accurate description of the parameter). It's not actually sensing what the fuel pump sees way at the back end of the car. If you have some sort of execessive voltage drop from the fuel pump relay to the pump (either because of faulty supply wiring, or a bad connection to chassis ground at the sending unit), then the pump may only be getting something much less than 12V (or whatever voltage your alternator is putting out).
Re: 86 tpi bogs and stumbles after driving when hot
Truest way to check the fuel system is put a temporary line off the test port to a pressure gauge. I run it from under the hood to into the car through an open window. You can also just leave it just behind the hood facing the windshield so you can see it. I always drive with a fire extinguisher (powder kind) when running this test just in case.
Then just drive around. It should stay between 37 and 45 (high vacuum, low vacuum) in all conditions (idle and WOT). If it does there is nothing wrong with the supply side.
Then when you shut off it should hold pressure for a minute otherwise you have a leaky injector.
Easy test, very helpful, take a little setup but worth it IMHO.
Re: 86 tpi bogs and stumbles after driving when hot
Originally Posted by Tootie Pang
Truest way to check the fuel system is put a temporary line off the test port to a pressure gauge. I run it from under the hood to into the car through an open window. You can also just leave it just behind the hood facing the windshield so you can see it. I always drive with a fire extinguisher (powder kind) when running this test just in case.
Then just drive around. It should stay between 37 and 45 (high vacuum, low vacuum) in all conditions (idle and WOT). If it does there is nothing wrong with the supply side.
Then when you shut off it should hold pressure for a minute otherwise you have a leaky injector.
Easy test, very helpful, take a little setup but worth it IMHO.
Yep I taped the gauge to the windshield and had it on the road for a minute after checking the pressure in the driveway, same result though, WOT pressure was 10 - 15 psi. Holds pressure for a bit but will have to re check the leakdown time
Re: 86 tpi bogs and stumbles after driving when hot
Originally Posted by 2012sergen11
Yep I taped the gauge to the windshield and had it on the road for a minute after checking the pressure in the driveway, same result though, WOT pressure was 10 - 15 psi. Holds pressure for a bit but will have to re check the leakdown time
09-25-2017, 10:30 AM
