[gtofreek]

I just thought back about my 1987 F.I. S-10 pickup. When I first got it, it wouldn't accelerate. It would idle fine but when I tried to rev it up, it would pop and carry on like it had a F.I. problem. I tried different parts to no avail. Finally someone told me to pull the oxygen sensor out and see if it would rev up. I did, and it did. Turned out the catalytic converter was plugged up. Replaced it and all was fine.

Does your's have a catalytic converter?

You can start it and with it idling, see how much exhaust pressure is coming out the tail pipe. If you can't feel it puffing on your hand, you may have a plugged cat converter on your hands.

[adynes]

Originally Posted by 1980 TA

I seem to have a wealth of data in the short run. Let me know what you want to see.

If you want, sent me the datalog file and I'll see if I can find anything. I'll pm my email address

[Squidward]

Where is JLMounce? I'm pretty sure he listens to efi audio books while he sleeps!

Data logging is good. I'd try to get a good graphical overly of rpm, tps, target afr, actual afr, map, fuel trim, etc. for various driving conditions - idle, cruise, wot. I'd be curious where the mismatch might be on target vs. Actual afr.

Since you have an o2 sensor fault, I'm not sure if your "displayed" afr will be accurate. You might want to also pull your plugs to validate rich or lean conditions on one/all cylinders. There is only one o2 sensor and a batch fire of fuel, so a faulty lean cylinder could cause all to be rich, or a misfiring cylinder might cause all to run lean. You would see a condition like that on your plugs or in the fuel trims.

[1980 TA]

See if this link for the data log will work.

https://1drv.ms/u/s!Ah1_BySMrA7yiluOZ3MMjWOOJUwU

I tried running it with the O2 sensor un hooked. The AFR's on the dash gauge were erratic compared to with it hooked up. Still couldn't get it to accept any throttle input.

Hopefully tomorrow I can go back through the ignition system and hook the timing light to each individual wire to make sure they are all sparking.

No catalytic converters on the car.

Emailed FITECH and hopefully they will send a response tomorrow.

[JLMounce]

Originally Posted by Squidward

Where is JLMounce? I'm pretty sure he listens to efi audio books while he sleeps!

Lol, I’ve been away from the computer!

OP the very first thing I would check is that there isn’t a vacuum leak at the throttle body base. That’s one of the more common issues that can cause a lean pop.

In regards to the o2 fault you’re seeing, that is normal on cold start. Original FiTexh models warmed the o2 sensor but that can cause shortened life. Later models have that feature turned off, so for about 20-30 seconds after start you’ll get an o2 temp fault. You can ignore that.

Are you running timing coontrol through the FiTech? If that’s the case, I would check to make sure the distributor hasn’t moved and that the advance is still locked out. If you do run timing control try unhooking that system and run the car traditionally with the distributor. If the problem is solved, you’ve gotta figure out what’s going on with the spark.

Off idle lean stumble is somewhat common with these systems after about 500-700 miles of learning. Watch what your AFR is doing when you try to come off idle. Do you have a rich or a lean bog occurring? Figure out which direction the AFR is running and go the opposite direction in the accel pump settings.

There are four settings that correlate to accel pump fueling. dTPSgain hits first and correlated to slow tps movements. Next is dTPS acc max. This is the maximum modifier for the dTPSgain. Try adding a couple percent to these which can help you out.

Next is Accel Pump and Fast Accel for the three temperature breakpoints. Accel pump is added after dTPSgain and correlates to the MAP signal. Fast Accel is last and uses a combination of the MAP and Alpha N maps with tps and correlates to your sharp transient situations, like stomping the throttle off idle.

These stack so work in order of dTPS > Accel > Fast Accel.

More often than not this situation is a lean stumble, but every once in a while the system will push rich in the transient event.

You’re going to also need to verify fuel pressure with a gauge. Considering this happened originally at a higher rpm, it’s possible you’ve got a fuel delivery issue. What fuel system are you running?

[Squidward]

Good info. I didn't know about the o2 fault.

I knew that Jason's Spidey Sense was tongling!

[adynes]

Does Fitech offer a way to view datalogs graphically? I gave the megasquirt software a try and it works, but only 500 data points at a time with the free version.
https://www.efianalytics.com/MegaLogViewer/

I think your O2 sensor is probably ok. It seems to respond appropriately to fueling pulsewidth. One change I would make is to richen up your target AFR at idle to something in the 13.5-14.0 range. It will make the idle and afr more stable. I can see in the data your idle afr jumps up and down quite a bit even with small changes in pw. I had the same issue with my megasquirt setup, trying to idle at stoichiometric afr. 13.5 worked a lot better for me, and helped transient throttle tip in too. Plugs stay clean as long as the engine is up to temperature and driven/loaded.

I think you issue isn't fuel related, but probably spark or valvetrain or something else. The screenshot below of your datalog I think shows the issue occuring. You have the throttle opened to 14% and then 17%, but the engine wont rev above ~1500 rpm. AFR looks fine here so I don't think fueling is the issue. You should be able to rev it to 1500 with small throttle opening, and the manifold pressure should drop (engine VE better at higher rpm), but it's actually increasing.

I'd go through the ignition system and inspect everything. What is your specific ignition setup? How is the Fitech triggered, and how does it control the coil?
I'd also do a compression or leakdown test, and check the valvetrain, rocker adjustment, valve lift, etc.
Maybe someone with Fitech experience will catch something I missed

[JLMounce]

FiTech does have the procal software available for it. It comes pre-loaded on the PA models and is on the handheld for download. If you don't have a PA version, you can get the procal software at this link. https://www.facebook.com/groups/1138...8395778560853/

adynes log view is helpful here but it's a bit hard to read since we can't see the vertical axis values. But you can see that your commanded spark advance here is hunting a bit, which it's doing to stabilize the idle against a fluctuating AFR. This tells me the oxygen sensor is seeing some erratic readings and you can see the trim trying to add fuel here. Most likely culprit is an oxygen leak in the exhaust system before the o2 sensor. Coul also be near but behind it. You need a minimum 18" of pipe behind the o2 sensor to avoid any type of reversion that can effect fueling.

You also have the lean tip-in issue I addressed earlier. If you take a look at the transient event in the log view, you can see you crack the throttle, then the afr starts to dip lean and the trim is trying to compensate. Without being able to see the values I can't tell by how much, but I would almost guess you're at the maximum trim, which is bad. The car is stumbling at this point so you let of the throttle and the trim recovers the AFR.

What cam selection do you have this on in the base map? The fact that the system is wanting to add trim at idle, tells me you're probably on the wrong cam profile and the VE tables are a bit too far off.

So here's what I would do to try and correct this.

1. Verify there are no vacuum leaks at the throttle body base
2. Verify there are no exhaust leaks before or within 18" after the oxygen sensor (likely areas are header flange and collector flange)
3. Verify the distributor hasn't moved and that the mechanical advance is locked out properly. Reset if needed
4. Check your valves as adynes suggested
5. Reset the system to factory defaults and reload the base map. I've found the pontiac engines will want a lower cam profile than you think. If you're unsure try cam profile 2

Drive the car for a couple hundred miles and you'll probably start to see that lean tip-in start to occur at that time. When this starts to occur, make incremental changes to dTPSgain Accel and Fast Accel. Don't go more than 5% in any direction at any one time. Creep up on it until you find what the engine likes.

You want to set your idle AFR for maximum vacuum, just like you would with a carb. Once the items above have been addressed, the system should be able to hold a steady idle and spark advance at idle, regardless of where you set the AFR. FWIW my 462 likes 14.3 at idle and will cruise as lean at 15:1 in it's sweet spot.

[adynes]

Jason, is there a throttle Accel enrichment variable that is specific to the warm-up period? From what I remember seeing in the datalog, the lean spike at tip-in is worse at the start of the log when coolant temp is low, the gets better as the engine warms.


Edit: I just re-read your first post where you mentioned the three temperature setpoints

[JLMounce]

Originally Posted by adynes

Jason, is there a throttle Accel enrichment variable that is specific to the warm-up period? From what I remember seeing in the datalog, the lean spike at tip-in is worse at the start of the log when coolant temp is low, the gets better as the engine warms.


Edit: I just re-read your first post where you mentioned the three temperature setpoints

Yup, the dTPS gain is always functioning since it's based completely off the TPS signal.

The Accel and Fast Accel tables have three breakpoints. 20, 65 and 170 degrees and will interpolate between those break points. You can change these breakpoints in the ProCal software. I actually need to do this on mine, fueling at around 140-150 degrees temp on my issue is problematic. Since my car is always garaged and never sees temps below about 40 when cold, I can modify that a bit.

What's really happening here is the added fueling to keep the intake runners wet. The pontiac engines have very large intakes with a lot of surface area, which is one of the reasons this issue crops up eventually, the base table just doesn't understand how much fuel film there is on these engines. It takes some hints from the provided CID, but that's it.

So what you're seeing in the graph is initially, all is well, but shortly after tip-in the runners dry up as not enough fuel is being provided, the engine goes lean then the trim freaks out, over corrects and causes a decaying oscillation between lean and rich until it finds itself.

That's a symptom of the "self learning" as there's simply too much adjustability between the trim and learn value (in some cases about 50-60% correction). Typically one the system has had a good amount of miles and varying conditions on it, it's good to turn off the learn and in some cases if your learn and trim values are very close to 0, also limit the trim amount.

I do think the OP does have something ignition related going on here, but this lean tip-in issue is also playing a part in his issue.

[1980 TA]

It was ignition related. I hooked the timing lead to each plug wire and found that #4 was firing but very erratic. On an unrelated note, a plastic timing light does not fare well if it slips out of your hand and lands in the mechanical fan. $99 case of butter fingers there.

I pulled the #4 plug and it was pretty wet, but it the edges were sharp. I replaced it for good measure. I did notice that it was not near as tight as I would have expected. There was also a little residue around the plug on the head. I wonder if it wasn't getting a little blow by for some time.

After replacing the plug, I started it and still noticed a weak and erratic spark on #4. Popped the cap and everything under the cap looked good. I inspected the rotor and found that the screw locking down the adjustable rotor was loose. Added a bit of Loctite and tightened it back up. I could see an depression in the plastic from the washer and lined it back up there. Checked it at 2000 rpms and it was still spot on for timing.

I think I had two things going on. A somewhat loose plug and the loose rotor. Took it for a test drive and the readings on the FITECH were far more consistent and smooth. AFR values were much smoother, especially on the analog gauge on the dash (02 sensor is on the even side of the motor). Trim values were much smoother. It drove better than it ever had. MAP readings at 70 mph went from 45-48 to 37-38. Motor is working way more efficiently. Gonna have to drive it a while to let it fine tune the tables.

Thanks for all of the help from everyone.

Quick question about spark plugs. Mine are Autolite 25. It's been a while since I've looked at plugs, but I remember my previous Pontiac motors having a metal crush washer on them. The Autolite's seem like they use a taper to seal the hole. Do I have the right plugs? Little miffed that one was loose. I installed them 5000 miles ago while the engine was out and on the stand. I could see not getting one torqued well with the motor in the car and fighting all the obstacles but not on the engine stand. Live and learn.

Makes me want to check the torque on all of them when its back on the lift. I have to get the passenger side ones from below. Between AC and the G Braces, its almost impossible to get to them from the top.

Thanks again.

[1980 TA]

BTW I have it set at Cam profile #2. I originally tried #3 and thought it worked okay. Last summer I goofed and thought I was saving data and ended up loading baseline #2 to the handheld by mistake. I noticed that the car started much better with it there thinking it was a 350 and cam profile 2, so I adjusted the parameters to the correct sizes and ran with it. Been very pleased with it so far.

[JLMounce]

Definitely makes sense. Glad it was an easy fix for you!

[gtofreek]

For the spark plug type, what heads are you running?

[Squidward]

Originally Posted by JLMounce

FiTech does have the procal software available for it. It comes pre-loaded on the PA models and is on the handheld for download. If you don't have a PA version, you can get the procal software at this link. https://www.facebook.com/groups/1138...8395778560853/

I just joined, even tho I hate FB. I tried the procal software from somewhere on the web, but it wouldn't work right. It seems like having that software would be just too convenient.

I know enough of Excel to do a graphical analysis. It'd be nice if there was an Excel guru capable of creating a macro that did one click import into a preset analysis format. I work with engineers that do that kind of stuff with JUMP in their sleep. I am not that guru.

[Squidward]

1980 TA, nice work!

[JLMounce]

Originally Posted by Squidward

I just joined, even tho I hate FB. I tried the procal software from somewhere on the web, but it wouldn't work right. It seems like having that software would be just too convenient.

I know enough of Excel to do a graphical analysis. It'd be nice if there was an Excel guru capable of creating a macro that did one click import into a preset analysis format. I work with engineers that do that kind of stuff with JUMP in their sleep. I am not that guru.

There are k-line drivers that have to be installed first and that can be somewhat tricky at times. Especially because they are unverified and windows will try to block the install at several points.

I've never messed with the software, I just read the .csv when I take a log. The graphical format is nice for seeing multiple events in time though.

[adynes]

You guys should try the MegaLogViewer software from Efianalytics. It's a good tool.

https://www.efianalytics.com/MegaLogViewer/

[adynes]

I figured out how to get it to open the entire file, not just the first 500 points.

Open the datalog in Excel.
Save as: Text (tab delimited)
Find the new file and rename from "dashboard.txt" to "dashboard.msl"
If you can't see the file extension (.txt, .CSV, etc), go to the Control Panel in Windows, find "File Explorer Options" and uncheck "hide extensions for unknown file types"

[1980 TA]

As for spark plugs, the heads are 6x. The engine builder recommended R44TS for plugs and when I gave that number to the parts store, I got Autolite 25 as the in stock comparable. In reading the current spark plug thread, it looks like NGK are the way to go if someone would have the right part number for the 6x heads.