Probably some stupid questions from a noob

Discuss General Motors (GMC, Chevy, Pontiac, Hummer, Cadillac, etc) tuning topics here. Request definitions, discuss parameters, etc.

Moderators: robertisaar, dex

Post Reply
jjensen6823
Posts: 6
Joined: Fri Jul 17, 2015 7:33 am

Probably some stupid questions from a noob

Post by jjensen6823 » Wed Jul 22, 2015 3:08 pm

I just got my ALDL cable from RedDevilRiver, and I need some help understanding what I am seeing.

Background: '88 Fiero Formula, blew the motor ten years ago. Swapped in a Jasper crate 3.4L for a 95 F-body. Initially kept all Fiero externals including distributor, but was never happy with the set up.

After doing a lot of reading, decided to use the F-body DIS instead. Grabbed a 7730 ECM and wiring harness from a 91 Sunbird 3.1, as well as the knock sensor, and used Ryan's conversion chart on gmtuners.com to repin the Fiero and run the additional wires necessary. Got an aluminum adapter plate so I can use the digital EGR. Hooked everything up and it started right up but ran rich. Sent memcal to Ryan to be reprogrammed for a 3.4L. Still running rich and throwing EGR code all the time, often stalling at idle and refusing to idle on restart. Turns out I had a leaky EGR gasket between the Y pipe and the EGR stand off (yes, I reused the old gasket. It's not made any more.) Spent two days trying to find a replacement gasket before I got some high temp gasket material and cut my own. I think I did a pretty good job, and I don't think it's leaking (I did the soapy water test), but I could be wrong. I also found a replacement at Fierostore.com and ordered it. It came a couple days ago, but I haven't swapped it yet. I can if I need to.

Since installing the new (homemade) gasket, it runs MUCH better. But after 20 minutes or so of driving, the SES light comes on, and now I am throwing EGR and MAP trouble codes, and still running somewhat rich, though not as bad as before. After more reading, decided there were too many things it could be: O2 sensor and/or wiring, MAP sensor and/or wiring and/or vacuum, Coolant Temp Sensor and/or wiring, EGR gasket and/or wiring (I have two digital EGR's and have tested both to be sure they are working. I've installed both with the same results, so I am convinced it's not the valve), or it could be a leaking injector. Decided to invest in the ALDL connector.

Got everything installed and working, hooked up to the car, started her up and started data acquisition right away (still in open loop). I don't know if that was a bad idea or not. When I scanned down through the data. The "Target Air/Fuel Ratio" was red, with a value of 12.40. The only other red flags are the word "ERROR" in red next to "32 EGR" and "33 MAP High".

Suggestions? I don't think the EGR gasket is leaking, but I can swap for the one from the Fiero store. I don't think there's a vacuum leak on the MAP, but maybe I'm wrong. My vacuum gauge tool got crushed in the toolbox a while back, so I don't have one right now. Bad MAP? Bad O2? Wiring? Any thoughts?

robertisaar
Author of Defs
Posts: 962
Joined: Sat Feb 21, 2009 3:18 pm
Location: Camden, MI

Post by robertisaar » Fri Jul 24, 2015 1:34 pm

your MAP sensor needs sorted out before anything else. that and the crank sensor are easily the two most critical sensors on the engine.

for the moment, I would block off the EGR port to eliminate the possibility of a vacuum leak or an EGR valve stuck partially open and causing recirculation at all times. oddly enough, the side of a soda can actually works pretty well as a temporary plug.

in any case, need to see what the MAP sensor is doing. idling, you'll probably be in the 30-40kPa range and have somewhere between 10 and 30 IAC steps.

clearing the codes via mode 10 commands while running may be helpful as well. right-click anywhere in the row of icons at the top of tunerpro, make sure "data acquisition send command" is enabled and you should have the ability to send a clear codes request to the ECM. it may require a few clicks to get the ECM to actually receive the command, so don't be surprised if you have to send it 5 times or so to actually clear the code.

jjensen6823
Posts: 6
Joined: Fri Jul 17, 2015 7:33 am

Post by jjensen6823 » Fri Jul 24, 2015 2:51 pm

Thank you so much for taking the time to reply. I replaced my fuel pressure regulator (because there were some gas fumes in the MAP vacuum tube--not much, but I really want this fixed!), and I also replaced the vacuum lines with ones from another Fiero that were in much better condition. The first time I ran the car, the SES light was on and the exhaust smelled absolutely awful. I let it run awhile, but it didn't get better, so I shut it down until I could hook up the computer.

When I restarted it a few minutes ago, the SES light was out, and I can smell the exhaust a little bit, but it's not filling my garage with fumes this time. I hooked up tunerpro RT. Here are some numbers I want to ask about. First, there are two sets of coolant temperature numbers. Not sure why. But they are:

Coolant Temp:96.5
Coolant Temp at Start-Up:66.5
MAT: 30-31
Coolant Temp:201.65
Coolant Temp at Start-Up:151.7

Why so different? Do I have a bad sensor?

Map fluctuates up and down between 32 and 38
O2 Sensor bounces back and forth between 50ish and 850ish. Is that much fluctuation normal?
Target Air/Fuel Ratio:14.70
Then there's another MAP that fluctuates between 1.2 and 1.4
IAC Position is holding steady at 37-38
IAC Minimum Position:35
Step Change Command:00
Catalytic Temp:345
Spark advance bounces back and forth between about 20 and about 27

I show Codes 33, 34 and 54 in TunerPro RT, but the SES light is not on and it's idling fairly nicely without stinking up my garage. I wonder if the codes are left over. "Data acquisition send command" is checked, but I don't see how to actually send the clear command request. Can you tell me where that is?

robertisaar
Author of Defs
Posts: 962
Joined: Sat Feb 21, 2009 3:18 pm
Location: Camden, MI

Post by robertisaar » Fri Jul 24, 2015 3:59 pm

http://i.imgur.com/fIX47XN.png

if you have sendable commands in your ADX, you'll see something like that. if not, you'll just have a blank box.

happen to know what mask the ADX or calibration is? I imagine it is going to be 88 or A1, both of which have the ability to send a clear codes command.

with the SES light being off, I believe you're correct about them not being active, just history codes, but clearing them would verify this.

the two sets of temps are *F vs *C. nothing odd there.

MAP seems okay, O2 seems okay, the other MAP value is likely MAP voltage and seems normal. everything actually looks how I would expect it to. IAC seems a little high to me, but that could have many causes and eventually be determined as normal.

jjensen6823
Posts: 6
Joined: Fri Jul 17, 2015 7:33 am

Post by jjensen6823 » Sat Jul 25, 2015 6:03 am

Okay, I must be really dense, because I am using the $A1 code mask from the RedDevilRiver CD (1991-93 3.1 F body), but the box where commands should be is blank. What do I have set up wrong?

The SES light is back on again, but this time the code is "Fuel Pump Voltage." TunerPro shows a Fuel Pump Voltage of 0, but the car runs, so I figure it must be a wiring problem.

I'm still have the following problem, though: when I start the car while hot, it won't idle and immediately stalls. If I hit the gas a little as I start it and hold the RPM's up for a few seconds, the when I take my foot off the gas it idles fine. It also feels to me like it bogs down under Wide Open Throttle conditions. I took it for a test drive and recorded it in TunerPro. If anyone could take a look at it and help me get my car running properly for the first time in 12 years, I would be forever grateful! Is there a way to upload it to the Forum?

robertisaar
Author of Defs
Posts: 962
Joined: Sat Feb 21, 2009 3:18 pm
Location: Camden, MI

Post by robertisaar » Sat Jul 25, 2015 8:36 am

https://www.dropbox.com/s/ep4wuzdq4bemq54/A1.adx?dl=0

there is my A1 ADX, which has the mode 10 command in it already.

pump voltage showing 0 and running, I would look at wiring as well. on a 1227730, should be pin E13 for the fuel pump voltage feed. that can actually cause some problems since some calculations are done using fuel pump voltage as a reference.

jjensen6823
Posts: 6
Joined: Fri Jul 17, 2015 7:33 am

Post by jjensen6823 » Sat Jul 25, 2015 10:58 am

I'm done with that car. Pulled the plug off the ECM and check the terminal, had 13.5V, so I plugged it back in, and the Fuel Pump Voltage problem went away. Took it for a test drive--it frequently stalls when disengage the clutch, but not always. Sometimes, it idles fine. The exhaust stinks again, the SES light is back on, and it's the EGR code again. I obviously don't have a clue what I am doing!

I loaded your code mask, and now I have the commands. Thank you. This time (using your definitions) the second MAT item was red, reading 114. I give up.

robertisaar
Author of Defs
Posts: 962
Joined: Sat Feb 21, 2009 3:18 pm
Location: Camden, MI

Post by robertisaar » Sat Jul 25, 2015 6:12 pm

i don't mean to dump on anyone's tuning capabilities without reason, but this wouldn't be the first time I've heard about one of Ryan's calibrations for a 60V6 being finicky.

the reason the MAT value was red was likely that I setup an "alarm" limit under where you were seeing. it isn't necessarily a bad thing, probably an artifact of when I was using it and just never got disabled.

jjensen6823
Posts: 6
Joined: Fri Jul 17, 2015 7:33 am

Post by jjensen6823 » Sun Jul 26, 2015 1:22 am

It's funny you should say that, because I swear it ran better before I sent the chip to Ryan (even though it was programmed for a 3.1L). I don't remember it ever stalling at idle until right after I got the chip back. Unfortunately, I know nothing about tuning, so it's not like I am in any position to evaluate the programming (except by how the car runs).

Speaking about the EGR for a moment: I tested both of the EGR's I have and all three solinoids seem to be working correctly on both units. I removed the upper plenum and checked the EGR passage for blockage and removed the EGR tube and checked it--it didn't seem to be leaking. I ran a long wire from the battery into the passenger compartment and touched it to each of the three pins on the green (E/F) ECM plug (with it unplugged from the ECM of course), and all three solinoids clicked open and closed properly. I replaced the leaky gasket between the exhaust y-pipe and the EGR stand-off (though I also got to wondering--how could exhaust gas leaking OUT of the EGR system into the engine compartment before reaching the valve affect performance?) So unless I connected the wrong pin to the wrong solinoid (even though I double and triple checked my work against the spreadsheet from sinster performance), or one of the solinoids isn't closing all the way (on both EGR's), or my ECM is fried, what could cause it to keep kicking EGR codes? Could the programming cause that? Could it be a bad sensor? Maybe a bad O2 sensor? And how on earth do I troubleshoot at this point?

jjensen6823
Posts: 6
Joined: Fri Jul 17, 2015 7:33 am

Post by jjensen6823 » Sun Jul 26, 2015 1:41 pm

First, let me say that I know I am way out of my league, I don't know anything about tuning, and I am finding it difficult to locate "Tuning Information for Beginners" anywhere. I don't know what some of the abbreviations mean, and I don't know what the correct values for anything are. I wouldn't even be doing this if I wasn't having problems. But I am.

Robert, I used the definitions you sent me on my last test drive, and when the SES light came on, I took a look at things. I have a really short recording of a few seconds' data if you want to see it, but what I noticed was the following:

MAT (Bold Red): 106.08
BLM: (Red) 117
Knock Counter (Bold Red) 231

and error code 32 EGR.

IF I understand correctly (and that's a big if) BLM is Block Learn Mode, and it refers to the overall fuel trim? And the goal is 128? What does it mean that mine's 117? And if Knock Counter is counting the number of predetonations occurring, then I'd have to think that 231 is not good.

Advice?

robertisaar
Author of Defs
Posts: 962
Joined: Sat Feb 21, 2009 3:18 pm
Location: Camden, MI

Post by robertisaar » Sun Jul 26, 2015 8:04 pm

the EGR is tested by the ECM while coming down from speed with little to no throttle. it monitors the MAP sensor, opens the small solenoid and watches for a change in the MAP signal. if the signal change is large enough, it considers that solenoid good and moves on to the next.

after testing all 3, if they all pass, no DTC. if one or more fails, I believe it doesn't immediately set a code, but it runs the test a second time, if it fails that, then the DTC is set.

I've had failures caused by both blockages and sticky solenoids/valves. have you tried actuating them with the engine running? 1 should cause a noticeable, temporary stumble, 2 should cause a bit more than that and get the idle lumpy and 3 might stall the engine. GM did release calibrations with more relaxed EGR test standards, but a tuner would generally start with one of those anyways.

MAT of 106*F isn't too unusual with this weather, the IAT(or actual MAT if you have it threaded into the intake manifold itself) will heatsoak to ~20 or 30*F above ambient temperatures pretty quickly. more if you draw from a warmer air location, but even cold-air drawpoints will suffer some.

BLM of 117 means: 117/128=.91
your long-term fuel trim is causing 91% of the fuel calculated to be delivered to keep the O2 sensor happy. that isn't too bad assuming the calibration limits aren't set there. beyond 10% and I would say fueling needs reworked, especially if it isn't consistent throughout the VE table. staying within 5%(122-134) is a pretty tight range and is more than sufficient to keep an engine from running consistently.

knock counter of 231... that's somewhat alarming. depending on when those knock counts occurred, you may have a serious rework of the spark table ahead of you. if you connect before cranking the engine, you should see 0 knock counts at the time, then while cranking, they'll rise due to all of the racket the starter is making, but once the engine is fired, they shouldn't accumulate much, if at all. the counter will roll over at 255 and start over at 0 if too many counts occur.

your short-term fuel trim is INT and its math works the same, it just moves much faster than BLM does. when INT is too far away from 128 for too long, the BLM moves towards the direction the INT is in and the INT starts moving back towards 128.

Post Reply