Mid/top-end loss and no "go" when mashing throttle - no codes
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Mid/top-end loss and no "go" when mashing throttle - no codes
Hi folks,
I've got a fresh (<50miles) rebuilt 1988 350 TPI, and it runs well, timed good, idles good, starts easily. It has new plugs (gapped to 0.035"), wires, cap, rotor, and pickup coil. Ignition coil seems fine, so haven't replaced it. Tested ICM at Napa, tests fine. Tach and engine are smooth. Fuel pressure good at rail. No codes are set.
Here's the issue: I can't chirp the tires or even get close to breaking loose, and it loses top end power, to the point where I can't accelerate up a hill easily, especially freeway speed (has a T5, 5th gear on freeway is a laggy up a hill). What else could I check? Everything runs fine aside from a loss in go-power, and no throw-back-in-seat feeling like my older '85 305 TPI. It's like it's not getting enough air/held-back, but I have a new air filter (K&N, clean, well oiled), and everything is open that I can see and not blocked. New cat that's got a few hundred miles on it, and brand new muffler as well.
Checked TPS with moates/TunerPro RT and TPS goes from .47 to 4.37 at WOT so that seems to check out. Could it be a bad MAF, and what readings would I see on TunerPro (airflow area) if so?
I've got a fresh (<50miles) rebuilt 1988 350 TPI, and it runs well, timed good, idles good, starts easily. It has new plugs (gapped to 0.035"), wires, cap, rotor, and pickup coil. Ignition coil seems fine, so haven't replaced it. Tested ICM at Napa, tests fine. Tach and engine are smooth. Fuel pressure good at rail. No codes are set.
Here's the issue: I can't chirp the tires or even get close to breaking loose, and it loses top end power, to the point where I can't accelerate up a hill easily, especially freeway speed (has a T5, 5th gear on freeway is a laggy up a hill). What else could I check? Everything runs fine aside from a loss in go-power, and no throw-back-in-seat feeling like my older '85 305 TPI. It's like it's not getting enough air/held-back, but I have a new air filter (K&N, clean, well oiled), and everything is open that I can see and not blocked. New cat that's got a few hundred miles on it, and brand new muffler as well.
Checked TPS with moates/TunerPro RT and TPS goes from .47 to 4.37 at WOT so that seems to check out. Could it be a bad MAF, and what readings would I see on TunerPro (airflow area) if so?
Last edited by super_kev; 04-17-2020 at 09:38 PM.
#2
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Exhaust restriction? Old muffler/bad cat?
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Parts w/check list above seems good, but what exactly did you do though... swapped an LB9 for an L98. Same ECM, and same size injectors? If it's holding back I would lean more towards a fueling issue. The MAF didn't seem to give you any trouble when you were running the LB9... correct?
- Rob
Edit: Unless this is another car entirely, and not a swap?
- Rob
Edit: Unless this is another car entirely, and not a swap?
Last edited by Street Lethal; 04-19-2020 at 04:09 PM.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
It had a L69 HO carb engine with T-5 in this 1986. Was tired, needed a rebuild, so bought a wrecked '1988 GTA (rear end damage), pulled all wiring, TPI setup (honestly all engine bay stuff from the 1988 and interior/dash/fuse/ecm), put it in the 86. So it's a 1988 350 TPI. Had the 350 professionally rebuilt while at it. I have GM's service/wiring manuals, and everything is soldered and heat shrinked (if splicing needed, just to lights/body) otherwise all is OEM uncut 1988 harness from wrecked GTA. I never fired it up before I pulled from the donor vehicle, so don't know about MAF integrity; which is why I was asking if I could monitor readings in TunerPro to see if it wasn't reading out properly under hard acceleration. Perhaps it's injectors? But would my symptoms above be bad injectors? Like I say runs well until I mash into it, and even then it runs smooth, just doesn't have power. I'll give SouthBend a call tomorrow, they are cheap enough.
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#8
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
I was just reading through your other thread in the tuning section. Can you post a datalog in either thread, because there is a way to check if something is off. Remember we are tuning fuel to a given amount of air. The air is a constant. Either the MAF is metering poorly, fuel pressure is dropping, or the injectors are garbage. A datalog will give plenty of clues...
- Rob
- Rob
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
I was just reading through your other thread in the tuning section. Can you post a datalog in either thread, because there is a way to check if something is off. Remember we are tuning fuel to a given amount of air. The air is a constant. Either the MAF is metering poorly, fuel pressure is dropping, or the injectors are garbage. A datalog will give plenty of clues...
- Rob
- Rob
Whats PE? I was only “tuning” to adjust fan turn on and off, and remove egr.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Pe is power enrichment, you need to datalog to try to determine what’s going on.
have you looked at your blm in cl ?
you might also want to do a custom tune with a manual bin as a starter. Like 89 vette manual apyp but recurve timing.
have you looked at your blm in cl ?
you might also want to do a custom tune with a manual bin as a starter. Like 89 vette manual apyp but recurve timing.
Last edited by Tuned Performance; 04-19-2020 at 05:57 PM.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Hi,
Check your throttle body sensor. Make sure it's putting out the correct voltage.
Check your throttle body sensor. Make sure it's putting out the correct voltage.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
yes your right, read it too quick at first.
Thanks
Thanks
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
So, about to run over and log this climbing the hill. Do these spec files (adx, xdf) look ok for logging? I just want to make sure I capture all the data you're looking for. I've logged with HPTuners, but not TunerPro RT so I'm not sure if there's anything else I need to set.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Im not sure if thats the $32B adx. where did you get it ?
I have attached a copy that I have used that should work.
Make sure you put the ecm in the 10k mode to connect and one connected disable the 10k jumper.
I have attached a copy that I have used that should work.
Make sure you put the ecm in the 10k mode to connect and one connected disable the 10k jumper.
Last edited by Tuned Performance; 04-19-2020 at 09:38 PM.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Ah shoot! Missed your reply. Well, here's the log, in 10k mode the entire time. Why do I need to switch it to the outside once it connects? I don't mind doing it, I just want to understand why that way I can remember it easier.
Started driving/recording at 0:
0:06 - SES light came on, headed south on freeway, 65mph in 5th, slight downhill
0:10 - Turned around, started from stop, up steep onramp north and long 2-3mile hillclimb
0:11 - 4th gear, 60mph
0:12 - 5th gear, slowing down now to 50mph, back to 4th
0:13 - 5th gear again, stayed in 5th until grade leveled out
0:14 - Slight acceleration on slight uphill grade
0:15 - SES light on again, then off, on again at 0:17, got off, town driving
Throttle doesn't seem to do much in response past 2.5-2.6 on the TPS.
Hopefully you can use this to get some info as I can't log again until tomorrow afternoon. This is the GTA's chip, that I dumped, changed fans to come on earlier, disabled EGR, and toggled from automatic (that GTA had) to manual (that L69 had). Shucks, wish I had caught that message about the a-b 10k jumper. And I am using a $32B.xdf (and 1227165_160 adx as well, which is $32B and I believe I got it from the gm efi forum, or my other longer thread in the DIY prom section).
Started driving/recording at 0:
0:06 - SES light came on, headed south on freeway, 65mph in 5th, slight downhill
0:10 - Turned around, started from stop, up steep onramp north and long 2-3mile hillclimb
0:11 - 4th gear, 60mph
0:12 - 5th gear, slowing down now to 50mph, back to 4th
0:13 - 5th gear again, stayed in 5th until grade leveled out
0:14 - Slight acceleration on slight uphill grade
0:15 - SES light on again, then off, on again at 0:17, got off, town driving
Throttle doesn't seem to do much in response past 2.5-2.6 on the TPS.
Hopefully you can use this to get some info as I can't log again until tomorrow afternoon. This is the GTA's chip, that I dumped, changed fans to come on earlier, disabled EGR, and toggled from automatic (that GTA had) to manual (that L69 had). Shucks, wish I had caught that message about the a-b 10k jumper. And I am using a $32B.xdf (and 1227165_160 adx as well, which is $32B and I believe I got it from the gm efi forum, or my other longer thread in the DIY prom section).
Last edited by super_kev; 04-19-2020 at 10:42 PM.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
First thing that came to mind was the knock sensor, but you'd hear pinging during uphill acceleration, which you didn't mention. If you did mention it, then sorry for missing it, but I lost track when I read this...
Say what?! Not to sidetrack your topic, but was this 1986 L69 car a Trans Am or an IROC? Not many of either ever existed. Might've been worth saving. I guess there's one less now.
Say what?! Not to sidetrack your topic, but was this 1986 L69 car a Trans Am or an IROC? Not many of either ever existed. Might've been worth saving. I guess there's one less now.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Yep, I know. A trans am, I think only 20-30 were made with the combo. As I did the swap years ago at the time I can’t remember what my reasoning was behind it, but no starting due to vapor lock in the heat rings a bell and it happened a lot. Now looking back might have been easier to stick with the l69 carb and hunted for missing parts and going that route. I think I still have some of the engine parts saved in boxes, so it’s not a complete loss, and I didn’t really hack anything up; but yes I’ve thought the same thing; what was I thinking?
Last edited by super_kev; 04-20-2020 at 08:30 AM.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
You might want to switch to $6e much better adx. Unfortunately the adx I have doesn't show much as far as timing goes. Im not sure the correct address values to put in to add new items. $6e adx already has the spark advance and retard. your running real lean blm looks almost locked at 150 and knock counts are high. believe running in 10k mode locks timing and this could be where the pinging is coming from.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Stock, original injectors. Cam - can't remember; not a "hot" cam but I believe it was an 80s corvette profile. How do I switch to a $6e? Just load it then log with a $6e adx? You're not talking switch/reburn the chip, correct?
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
I pulled and gapped all plugs this weekend and they looked normal to me, and I’ve pulled a few plugs in my lifetime. No oil or carbon buildups.
Last edited by super_kev; 04-20-2020 at 02:19 PM.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Yeah that was it, was too quick when selecting the XDF in Tuner Pro. Was saying to myself...; I knew people avoided AKXY like the plague, and when I happened to see that, I was like, hmm I now see why lol. But yeah, just uploaded the correct XDF and it looks good...
- Rob
- Rob
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Forgive me guys as this is the first time I am even looking at this XDF. Now, I would have to assume that the values in; SA - In WOT vs RPM are being added to SA vs RPM vs Load at WOT, correct?
Bob, your EBL has really spoiled me over the years...
- Rob
Bob, your EBL has really spoiled me over the years...
- Rob
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Originally Posted by super_kev
Stock, original injectors. Cam - can't remember; not a "hot" cam but I believe it was an 80s corvette profile. How do I switch to a $6e? Just load it then log with a $6e adx? You're not talking switch/reburn the chip, correct?
- Rob
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Originally Posted by super_kev
So I’ll await what you too gurus want me to do. Yes I have the oddball 88. Sheesh.
https://www.thirdgen.org/forums/diy-...ml#post5665738
The 1989 code ($6E) is better, but need to use a '89 BIN and the $6E definition file together....
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
This should have been done a long time ago Kevin...
https://www.thirdgen.org/forums/diy-...ml#post5665738
The 1989 code ($6E) is better, but need to use a '89 BIN and the $6E definition file together....
https://www.thirdgen.org/forums/diy-...ml#post5665738
The 1989 code ($6E) is better, but need to use a '89 BIN and the $6E definition file together....
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
- Rob
Not to derail the thread, but this is what I am referring to in regards to PE...;
- Rob
Last edited by Street Lethal; 04-20-2020 at 05:55 PM.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
So if I want to disable EGR in the $6E, it should already be disabled as the bin I downloaded has "Disable EGR if MAT < X" at 0.50 Deg F, so no changes need to be done, correct? What about the SES that might come up with no EGR equipment? The AXKY had a flag I could uncheck for the code. I'll also uncheck VATS Enable as I don't have it, and check the box for Manual Transmission. Anything else before burning?
I used the $6E ARAP bin from here: http://tunerpro.net/downloadBinDefs.htm#GM
I used the $6E ARAP bin from here: http://tunerpro.net/downloadBinDefs.htm#GM
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
super_kev send me a email at brianlvs@yahoo.com , having issues uploading a bin you might like to try.
will have to see how it runs and if fueling and timing need adjustment.
will have to see how it runs and if fueling and timing need adjustment.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
super_kev send me a email at brianlvs@yahoo.com , having issues uploading a bin you might like to try.
will have to see how it runs and if fueling and timing need adjustment.
will have to see how it runs and if fueling and timing need adjustment.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
I have tried to attach as a zip no go. Just stays on the file finder /upload page.
feel free to upload here. No rob I made it a virus to wipe out your ebl calibrations lmao.
feel free to upload here. No rob I made it a virus to wipe out your ebl calibrations lmao.
Last edited by Tuned Performance; 04-20-2020 at 08:38 PM.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Posted in my mega thread by accident last night, couldn't figure out why I couldn't see my post this morning, haha. Still acts like one is light on the throttle. This tune is much better, much more responsive. I do like the $6E definitions, dash, all the data one can see compared to the AXKY. Here's the log - different run than last time (different area) but still had a few places I shifted into 5th and it lagged from 65 to 50mph.
I shifted from a lagging 5th into 4th gear again to gain speed around 1:12 up a slight uphill (not the grade from earlier AXKY log).
Got off freeway and started up a hill the other way around 2:52, and shifted from 5th back into 4th gear around 3:56 to not get run over by a semi.
I shifted from a lagging 5th into 4th gear again to gain speed around 1:12 up a slight uphill (not the grade from earlier AXKY log).
Got off freeway and started up a hill the other way around 2:52, and shifted from 5th back into 4th gear around 3:56 to not get run over by a semi.
Last edited by super_kev; 04-21-2020 at 08:44 AM.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Nope std GTA/350 manifolds. The O2 value was bouncing all over; I saw it hit 300s and 500s a few times but yes it mainly moved centered around 450. Wouldn't that mean it's connected and no wire break? Edited above to add a few timestamp events (lagging areas) in the log.
Last edited by super_kev; 04-21-2020 at 08:43 AM.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
I watched 3/4 of the log. After I saw no closed loop operation I saw no o2 movement.
i guess the best way to try to diagnose it would be get it up to operating temp which it was at 196f.
back prove the ecm wire at d7 it’s a purple wire and observe voltage. Was the o2 swinging at the end of the log ?
ill watch it later today have to run some errands. Could also be at the connector at the o2 .
i guess the best way to try to diagnose it would be get it up to operating temp which it was at 196f.
back prove the ecm wire at d7 it’s a purple wire and observe voltage. Was the o2 swinging at the end of the log ?
ill watch it later today have to run some errands. Could also be at the connector at the o2 .
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Gotcha. Saw it bounce briefly into the 3s and hit a 5 starting around 3:14 for 20s or so, but I've never watched an O2 sensor - should the values be pretty smooth vs. so jumpy in the log? I take it the ECM is reporting a multiplication of voltage which is why it seems it moving so much, otherwise it'd be staying around 4.5V and moving between 4.2-4.6V or so, right? I'll test the wire this afternoon.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
The reading is in mv. Once to operating temp 5-600 f the o2 will swing .450 is the middle pint of the swing.
staing above or below the swing point will indicate rich or lean for a extended time. Above .450 mv is rich.
the blm will reflect this as well. Spot build up on a 02 from running rich will kill it as well.
staing above or below the swing point will indicate rich or lean for a extended time. Above .450 mv is rich.
the blm will reflect this as well. Spot build up on a 02 from running rich will kill it as well.
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Re: Mid/top-end loss and no "go" when mashing throttle - no codes
Ah, so what you're saying is that .450 is fine, which is where it's mainly at (aside from small blips either way at times that I see in the log as the ECM corrects for rich or lean). So that means no problem with O2 then... especially if engine runs fine, aside from this loss of power like the throttle isn't being put down more, perhaps due to fuel pressure drop under load? There's no studder or unevenness like I would expect if injectors were failing, and I wouldn't expect all 8 to suddenly fail and operate smoothly at a 50-60% capacity (just tossing out a random number there) without a few firing fully and causing a rugged sound due to more explosive and powerful combustion in a few cylinders that are getting full fuel.