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Boost Decay at Partial Throttle


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#21 JSwan

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Posted 13 August 2020 - 01:29 AM

View PostTurbo Cary, on 12 August 2020 - 04:24 AM, said:

You really need to get an AEM or Innovate wideband gauge. The narrow band isnt telling you anything it's more for show.

For example on my old SQ I ran a narrow band gauge for a while. It always went "rich" and I thought things were fine. I put an upgraded turbo on and it still ran ok without issues. I was also tuning it with a MAFT. I finally got an AEM wideband and on the first pull I saw I was only hitting 12.8 at WOT! That's way too lean. The narrow band had been just showing rich.

Having all the information at hand leads to the best possible diagnosis available. Once I saw what my ECU was actually doing for fueling I corrected the MAFT, did another pull and it ran much better/safer.

wow, i wouldn't have expected there to be such a swing in accuracy, just thought it might be something small to help with fine tuning.  i'm behind on the upgrade knowledge on these cars so guess i need to do some more research on the AEM wideband, you mentioned that earlier in the post last year as well.  Is that AEM going to stand alone as a single upgrade or will it require more than just that to bolt on and work (I.E. MAFT, New MAS, different plumbing etc.)?  I'm running the eclipse 1G MAS with all the nice polished pipes at the moment, but i would give all that up for a better running car of course :)
1989 TSI SHP - Upgrades: Marnal NJV Head, Ported/Polished/Gasket Matched, SS OS Valves, Schneider HD Springs, 14G TD05H, 1GMAS, Trilogy Injectors, Trilogy FPR, Custom Header by Chad, BS Removal, 2.5" TEP Downpipe/B-Pipe/HKS Exhaust (no cats oops)/4"Tip, *DM/101 Hardpipes, HKS Type BOV, Walbro 255 Fuel Pump, SS Fuel Lines, BOSCH Red Coil, S&M Strut Bar, Poly Bushings, Polk Audio/Sherwood AMP/w/8" Sub, and Polished SHP Rims.  Working on Custom Interior, Brake Upgrades and Always on the Look for Hood Mods Including 83, Cowl, or Firebird Type.





#22 Turbo Cary

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Posted 13 August 2020 - 08:09 AM

View PostJSwan, on 13 August 2020 - 01:29 AM, said:



wow, i wouldn't have expected there to be such a swing in accuracy, just thought it might be something small to help with fine tuning.  i'm behind on the upgrade knowledge on these cars so guess i need to do some more research on the AEM wideband, you mentioned that earlier in the post last year as well.  Is that AEM going to stand alone as a single upgrade or will it require more than just that to bolt on and work (I.E. MAFT, New MAS, different plumbing etc.)?  I'm running the eclipse 1G MAS with all the nice polished pipes at the moment, but i would give all that up for a better running car of course :)

The wideband is just a sensor. You can either remove the factory one and use the new sensor/gauge to send information back to the ECU or just install a second oxygen sensor bung (usually supplied with the new sensor) have it welded in, and run the sensor not connected to the ECU.

I recommend AEM because it self calibrates and is easy to install/setup. There is a output wire from the gauge that can send information to the ECU. I had mine setup that way and it worked for years without issue.

#23 JSwan

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Posted 28 August 2020 - 12:58 AM

Guys, had some time to work this over the last couple weeks.  Here is an update.  Sorry i didn't quite troubleshoot like suggested cause my fleet mechanic had some time to spare late one afternoon so i had him throw the new injectors on before i got to run the car with different plug gapping.  Anyway, I found I was running NGK 7031 (BUR7EA-11) plugs gapped at 0.36 when the boost would not hold 12psi and before the new injectors.  Found one plug was somehow gapped much lower at 0.29 for whatever reason.  After reading some other posts about trying some different plug temperatures when tuning, I ran to the auto shop before they closed the first night to grab a different set of plugs to play with the plug temperature a bit and bought a set of 7133 (BPR6ES), which I think were a stock plug from the 1987 model year that run a little hotter than the NGK 7 series.  I gapped the new 6ES plugs at 0.35 as a starting point.  Rechecked the timing to confirm ~10btc (jumps around some).  Checked TPS voltage and found it at 4.7.  Checked CTS with meter and didn't get any readings that made sense (suspect my meter is dying) so i just unplugged it at engine startup and plugged it back in/out while idling and found the idle moved around between in/out so its providing some info to the ECU.  Tested ignition and found cylinder #4 plug wire was intermintently shorting and then pulled it off and it came apart (new Magnacore wires can't believe it).  So i replaced it temporarily with a cheap plug wire (had to buy the whole cheap set).  After all this, took it out for a spin.  Boost held at 12psi no problem and the car showed some wow factor.  Throttle was crisp and when hitting boost, 5psi felt more like it was on 5psi boost than before.  After driving it for a while maybe 15 minutes, i noticed quite a decrease in performance the hotter the engine got and after about 30 minutes it was difficult to even get back home.  Based on the A/F gauge behavior and throwing O2 codes, brought it home to inspect starting with fuel pressure.  My fuel pressure gauge was showing 39psi before i left home and 30psi when i got back.  New Walbro pump was whining more upon return as well.  Stopped for the week since i was POd at this point.  

So, here is where i am as of today and after a week to cool off and tinker more.  Reset the fuel pressure this time on a hot engine to 43.5psi, the recommended pressure from Trilogy, my injector manufacturer and other folks here on the boards.  It seems to be holding at 43.5 even after 30 minutes of driving so i assume fuel pressure must need to be set on a hot engine, or i have an another problem to contend with.  BTW, I notice fuel pressure drops by 10psi immediately after shutting the engine off and is back to 0psi after about 30 minutes from shut down. Besides this at the moment, my biggest problem is even with the new injectors and required higher (correct) fuel pressure, there is still a lean stumble between gear shifts particularly between 1st and 2nd gear and occasionally on light throttle.  You can feel the stumble and see it on the A/F gauge, which i'm still using the narrow band for now but it confirms what you feel.  Also, still at idle i'm showing lean when before the car sat it would always idle one bar rich like it was suppose to and smoother than it does now.  

Other misc. info.  I can hear the fuel pump humming along steady and when the 3 fans come on (i have them jumped), i can hear the pitch lower like it decreased its flow once the fans come on and then pickup pitch when they stop.  You can follow this from the engine bay while watching the the fuel pressure gauge.  From cold engine to hot engine, you can see each time the fans kick on, i will loose about 0.5psi of fuel pressure until it finally bottoms out at the 43.5psi i set it at on the hot engine.  I have reworked 6 of the 11 grounds spelled out in the service manual to date and replaced all the upper fuseable links and cleaned the bottom set and all terminals.  

Idle vacuum on my gauge is about 19"-20", so i think that's solid and doesn't indicate a vacuum leak.  i did an AC, EGR and Secondary Air Filter delete years ago, but i didn't remove all the solenoid valves and little things, just plugged nipples that were open and plated the EGR base on the intake.    

What should i try next?  What problems are you all suspecting i still have?  Sorry for the long re-post here but i wanted to give everyone as much detail as i could.

J
1989 TSI SHP - Upgrades: Marnal NJV Head, Ported/Polished/Gasket Matched, SS OS Valves, Schneider HD Springs, 14G TD05H, 1GMAS, Trilogy Injectors, Trilogy FPR, Custom Header by Chad, BS Removal, 2.5" TEP Downpipe/B-Pipe/HKS Exhaust (no cats oops)/4"Tip, *DM/101 Hardpipes, HKS Type BOV, Walbro 255 Fuel Pump, SS Fuel Lines, BOSCH Red Coil, S&M Strut Bar, Poly Bushings, Polk Audio/Sherwood AMP/w/8" Sub, and Polished SHP Rims.  Working on Custom Interior, Brake Upgrades and Always on the Look for Hood Mods Including 83, Cowl, or Firebird Type.

#24 Turbo Cary

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Posted 28 August 2020 - 05:50 AM

You have to do things one at a time. Doing multiple changes isn't going to help fix the main concern.

You have your fans jumped, and you say fuel pressure drops when they come online. That's because it takes a good bit of electrical load to get the fans going and it's taxing your electrical system. Fans should be set up as primary, secondary, and AC. One fan should come on at X temp. Then if it is still getting too hot the next comes on at Y temp. If they are all jumped together and they all come on at the same time you're really taxing the tiny alternator that these cars come with.

If you haven't done a Hyundai alternator upgrade I recommend doing that. What type of fans are you running btw? Stock ones or aftermarket?

As for the decrease in boost as the engine warms you really need to do a cold and hot compression test. That will help eliminate a mechanical fault on a specific cylinder, do a cylinder leakage test as well. If you're running a jet valve head you could have a crack and not know it.

As for the plugs go back to regular heat range, gap them down to 0.28 higher boost levels call for a smaller gap. Even if you arent hitting 20 something psi it is easier for spark to jump across a smaller gap with increased cylinder pressure.

If you arent running AC, EGR etc just remove all the solenoids. Simplify the engine bay.

The CTS is crucial to engine operation. If it fails or reads wrong your whole AFR will be out of whack. When mine failed it ran super rich and barely would drive.

What MAF sensor are you using? do you have spares and have you tried swapping any out? Do you have a blow off valve on the engine at all? Can you post pictures of your engine bay/setup?

Lastly get the dang wideband so you can really see what AFR you are actually at!

#25 JSwan

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Posted 28 August 2020 - 10:29 AM

View PostTurbo Cary, on 28 August 2020 - 05:50 AM, said:

You have to do things one at a time. Doing multiple changes isn't going to help fix the main concern.

You have your fans jumped, and you say fuel pressure drops when they come online. That's because it takes a good bit of electrical load to get the fans going and it's taxing your electrical system. Fans should be set up as primary, secondary, and AC. One fan should come on at X temp. Then if it is still getting too hot the next comes on at Y temp. If they are all jumped together and they all come on at the same time you're really taxing the tiny alternator that these cars come with.

If you haven't done a Hyundai alternator upgrade I recommend doing that. What type of fans are you running btw? Stock ones or aftermarket?

As for the decrease in boost as the engine warms you really need to do a cold and hot compression test. That will help eliminate a mechanical fault on a specific cylinder, do a cylinder leakage test as well. If you're running a jet valve head you could have a crack and not know it.

As for the plugs go back to regular heat range, gap them down to 0.28 higher boost levels call for a smaller gap. Even if you arent hitting 20 something psi it is easier for spark to jump across a smaller gap with increased cylinder pressure.

If you arent running AC, EGR etc just remove all the solenoids. Simplify the engine bay.

The CTS is crucial to engine operation. If it fails or reads wrong your whole AFR will be out of whack. When mine failed it ran super rich and barely would drive.

What MAF sensor are you using? do you have spares and have you tried swapping any out? Do you have a blow off valve on the engine at all? Can you post pictures of your engine bay/setup?

Lastly get the dang wideband so you can really see what AFR you are actually at!

Thanks for the input Turbo Cary.  I have the GM 115 alternator upgrade and still using all 3 stock fans.  i had my fleet mechanic do a compression test and forgot to mention that previously.  Warm engine found 115 in all 4 cylinders but he didn't open the throttle plate during the testing, but no variance in compression.  I have a Marnel non jet-valve head i bought new that has less than 10k miles on it and never got past 1/2 on the temp gauge.  I will play around with the plugs and gaps one set at a time now that the car is getting closer to tuning up and will look into that dang wideband.   I will get a new volt meter and test that CTS through all the temp ranges.  I'm using the eclispe 1G MAF and i do have a spare but the honey comb fell out while installed stranding me years ago so i swapped it out with another.  i think i can glue it back in?  yes i have a BOV.  i'm not sure how to post photos on these boards, but i will give it a whirl.  

Driving it into work this AM, it really is running better other than that lean sputter.  My TPS has been replaced once before with brand new, but wonder if i should do a sweep test thinking it might a contributor to the lean sputter at light throttle?
1989 TSI SHP - Upgrades: Marnal NJV Head, Ported/Polished/Gasket Matched, SS OS Valves, Schneider HD Springs, 14G TD05H, 1GMAS, Trilogy Injectors, Trilogy FPR, Custom Header by Chad, BS Removal, 2.5" TEP Downpipe/B-Pipe/HKS Exhaust (no cats oops)/4"Tip, *DM/101 Hardpipes, HKS Type BOV, Walbro 255 Fuel Pump, SS Fuel Lines, BOSCH Red Coil, S&M Strut Bar, Poly Bushings, Polk Audio/Sherwood AMP/w/8" Sub, and Polished SHP Rims.  Working on Custom Interior, Brake Upgrades and Always on the Look for Hood Mods Including 83, Cowl, or Firebird Type.

#26 Turbo Cary

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Posted 28 August 2020 - 11:28 AM

What type of BOV are you running and is it adjusted right? You could be pushing it open under boost but it would flutter or be noticable if that was the case.

The lean spike you're seeing in between shifts could be the bov taking too long to close and allowing unmetered air to bypass the maf.

Ideally BOVs should be recirculated back into the MAF pipe to keep the turbo spooled and the intake system sealed.

#27 JSwan

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Posted 29 August 2020 - 01:32 AM

MK1 OVCP and HKS type BOV.  no flutter or sound until boost gets close to 0-1psi on non-factory boost gauge, then a light discharge between shifts.  gets louder under more boost build between shifts.,  i think i still have my stock OVCP so i will try it tomorrow and see what happens to rule the BOV in/out as a problem.
1989 TSI SHP - Upgrades: Marnal NJV Head, Ported/Polished/Gasket Matched, SS OS Valves, Schneider HD Springs, 14G TD05H, 1GMAS, Trilogy Injectors, Trilogy FPR, Custom Header by Chad, BS Removal, 2.5" TEP Downpipe/B-Pipe/HKS Exhaust (no cats oops)/4"Tip, *DM/101 Hardpipes, HKS Type BOV, Walbro 255 Fuel Pump, SS Fuel Lines, BOSCH Red Coil, S&M Strut Bar, Poly Bushings, Polk Audio/Sherwood AMP/w/8" Sub, and Polished SHP Rims.  Working on Custom Interior, Brake Upgrades and Always on the Look for Hood Mods Including 83, Cowl, or Firebird Type.

#28 JSwan

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Posted 06 September 2020 - 01:07 PM

Fellas,  swapped out my OVCP/BOV combo and put the stock OVCP back on.  Plugged intake manifold nipple that was source for the BOV and re-installed the boost source hose to the wastegate.  This fully eliminates the BOV from the equation.  No change, still lean condition and slight hesitation between shifts at 1st and 2nd and other light/moderate throttle inputs. Got to thinking this is similar to when your secondary injector goes bad and tracked the problem to around 2500-3000rpm on light throttle.  So...I removed the injector clips and swapped them around.  The car will not idle when the primary injector clip is connected to the primary injector.  It has been running decent with the hesitation I'm talking about with the clips reversed, i.e. primary clip on secondary injector and secondary clip on primary injector.

So., i got to looking and the wiring harness into the clips and found a post on the board where it tells you which color wire goes into which side of the clip, as there is a positive and negative side of the clip itself.  i noticed the color scheme in the post doesn't match what my wiring harness has.  My secondary injector clip leads are both white with blue tracers and the primary injector clip leads are white with black tracer and white with white tracer.  So i have the primary injector clip and leads correct but i can't tell which is positive and which is negative from the wiring harness for the secondary injector since both wires are white with blue tracers.  Not sure how big of a deal this is, but i'm just throwing it out there as an observation.  

I'm going to try installing my older secondary injector in the new primary injector location since i know the car will idle better with a 950cc injector on the primary clip and see how the car runs.  i expect the car will idle and not have hesitations on small to moderate throttle inputs but it will probably run richer on boost because i'll be using two 950cc injectors but the car has been running lean with the primary injector so why not see what happens.  It could be necessary for the mods i have, which are not all that aggressive really.  If not, i'll swap all the injectors back to normal and then proceed to replacing the 1G MAS with the other 1G MAS one i just repaired and see what happens then.  i will report back...but any comments are welcome....
1989 TSI SHP - Upgrades: Marnal NJV Head, Ported/Polished/Gasket Matched, SS OS Valves, Schneider HD Springs, 14G TD05H, 1GMAS, Trilogy Injectors, Trilogy FPR, Custom Header by Chad, BS Removal, 2.5" TEP Downpipe/B-Pipe/HKS Exhaust (no cats oops)/4"Tip, *DM/101 Hardpipes, HKS Type BOV, Walbro 255 Fuel Pump, SS Fuel Lines, BOSCH Red Coil, S&M Strut Bar, Poly Bushings, Polk Audio/Sherwood AMP/w/8" Sub, and Polished SHP Rims.  Working on Custom Interior, Brake Upgrades and Always on the Look for Hood Mods Including 83, Cowl, or Firebird Type.

#29 JSwan

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Posted 06 October 2020 - 01:14 AM

Well, two secondary injectors did what i expected.  Idle and light throttle were great, then a flooding backfire under moderate throttle.  So, i swapped back the primary injector in the correct port and replaced my first 1G MAS with a second 1G MAS that I repaired the larger honeycomb (it was loose and fell out while installed years ago).  After swapping these items, the car idled decent and ran just fine with the second 1G.  No lean condition and power was very good at light to moderate throttle.  Never got to really crowd it.  After driving for about 15 minutes, tested up to 4lbs of boost on the highway and to an easy and quick 95mph, still no problems.  Brought it home and shut it down for about 10 minutes and then went back out.  Within 5 minutes, 1 mile from the house i heard a large pop and the engine died.  Car wouldn't start.  It rolled over just fine, seemed like it wasn't getting spark, air or fuel.  Tried bumping the throttle a few times while cranking and the car just popped and backfired like a gunshot.  

I suspected that the 1G MAS i just replaced lost the honeycomb again.  Pulled it apart tonight and its intact, no visible problems.  Began inspecting this 1G MAS and feel like it has been tampered with at some point.  Its missing the black backing clip on the brown piece.  I took some photos of this one and my second 1G MAS (which is missing the lower honeycomb).

20201005 221716c
Album: 1G MAS
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Tried to attached from my Gallery, hope everyone can see the two 1G MAS, i added some descriptions.

Question, is there any other mod on the 1G that people have done to further enhance performance on the Starquest?  I feel like both my 1G MASs have different problems.  First one has a missing backer plate between the brown piece and the main body of the MAS and the second one is missing the lower honeycomb.  I'm thinking the second one is a problem because this honeycomb can't be removed, it could be causing my problem with the lean conditions at idle and light throttle and its the one i had on the car when i first posted.  It ran fine for years but now it won't idle with new injectors and has lean spots at low throttle and trips my 02 sensor with my other set of injectors (same Trilogy injectors).  I don't know what is wrong with the first 1G MAS, but maybe someone tampered with it before i owned it to try and improve performance.  It seemingly idles better than the other, runs stronger in all phases and doesn't have the lean partial throttle.  But now it might be dead, not sure.  Maybe it quit and thats the pop i heard or the aftermath of it dying on me.

Don't know where to go from here but to find another 1G MAS to try on the car.  Any other suggestions?
1989 TSI SHP - Upgrades: Marnal NJV Head, Ported/Polished/Gasket Matched, SS OS Valves, Schneider HD Springs, 14G TD05H, 1GMAS, Trilogy Injectors, Trilogy FPR, Custom Header by Chad, BS Removal, 2.5" TEP Downpipe/B-Pipe/HKS Exhaust (no cats oops)/4"Tip, *DM/101 Hardpipes, HKS Type BOV, Walbro 255 Fuel Pump, SS Fuel Lines, BOSCH Red Coil, S&M Strut Bar, Poly Bushings, Polk Audio/Sherwood AMP/w/8" Sub, and Polished SHP Rims.  Working on Custom Interior, Brake Upgrades and Always on the Look for Hood Mods Including 83, Cowl, or Firebird Type.




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