WOT pull, RPM's Drop?
 

Hi all

Firstly ive been reading here for about 18 months, preparing to turbo my car
:) thanks for all the good threads and esp the FAQ.

My set up is ( and thinking about it i will update my sig, its been installed 6 hours ) '90 NA with no A/c or p/s 210k k/m, garrett turbo with a .48 AR compresser side not sure about exhaust, FMIC, 330cc injectors, full 2.5" exhaust with hi flow cat, Link mk2 ecu, recirc BoV, currently on stock plugs, just brought some bkr7e that will go in tomorrow and gapped at .028-.030. Location Tasmania AUS

Ok i know, the link isnt great. im saving for a MS and will be comming shortly.

While i was tuning today i was making a WOT pull in 3rd gear and got to 6k rpm and with my foot flat to the floor my tach was going down. ive attatched a log of this with just MAP and RPM. Ive searched and came up pretty dry, maybe the igniter is dieing? I can get a pic with more data on it if required. I can do some basic trouble shooting but im very new to this as this is my first turbo car and first time driving one even.

Thank
Scott


Ps... Build thread up in a few days once i have the car semi sorted.

What size turbo are you using? The A/R tells us nothing without knowing the size of the turbo itself. I'm wondering just how tiny is tiny?

I'm Embarassed to say that all i know is its a T28 with a .48 compresser side. I recieved the turbo on the manifold with lines attatched and wasnt able to see any markings of the exhaust side.
I had a friend that build's drag cars look at it and he said that it looked to be in good condition so i just proceeded with the install.

Scott

Is it possible you have some sort of rev limiter soft cut at 6000RPM and it's pulling out ignition heavily?

Thanks for the reply :brain: :)

i thought the same and read up in the manual.

Sets the rev limit for the engine. Hard limit (fuel cut off) occurs at the
set point. Soft limit occurs at 300 RPM before the set point by reducing boost, and also trailing
off ignition timing.

Ive added a pic showing that same pull but with my ignition advance shown, it doesnt appear to be pulling timing. Its at 18deg pretty much all the time at max boost ( note i havent done any spark tuning and dont really intend to untill i hit the dyno probibly with a MS rather than the link )

Check the default Link 1.6 turbo map you can pull off FM's website; your timing should be adjusting under boost if you are running the right map. I would not do any more WOT pulls under boost until you normalize your Link timing map to the FM map. Also, Link 1.6 default injectors are 440cc, I'd be a little concerned running under boost until I was sure I had the smaller injectors properly scaled in the Link. You aren't going to be able to run a lot of boost without maxing out those small injectors. how much boost are you running??

Sorry i should have clarified :). Im currently using a map that was modified from the FM maps and was being ran on the car with the setup im currently using ( brought all the gear as a "kit" ) Its basically the 1.6L 440 cc map with master fuel set to 125 ( 25% more fuel over the whole map ) to make up for the difference in injector size. Im using det cans currently and not experiencing any detonation at max boost of 150 kpa about 7 psi. The max injector usage % for that pull was 64% so i have a little head room before 80%.

i can post a pic with Afr aswell, although my PC reads leaner than it really is so the graph is a little off, its actaully 0.3 richer than the graph suggests, ill be moving my WB02 grounds to ecu grounds to see if this sorts it out as i know the conversion file is correct. im still tuning fuel values so they are a bit off what id like for safty but there hasnt been any pinging/detonation so i think im ok.

I will be gapping new plugs today that were recomended here and might give that a try unless you think its a bad idea to do any more WOT pulls. Ive never experienced spark blow out so im hopign that might be an issue and caused the tach to have a hissy fit. ill post up a pic of a/f At the time of the RPM drop i was at 12.6/1 AFR and 148kpa.

My timing tapers from 28 deg at 55 kpa to 18 deg at 150kpa ( AUX CF is my wideband )

Added timing and fuel map, fuel is still over the show a little, tuning it currently. Timing is in 1/4 of a degree so 40 in the pic = 10 deg

Thanks again all - It might be a few days untill i next update this have a busy weekend :) looking forward to sort this out and getting some tuning done.

Scott

just for the sake of hilarity, can you show a log with TPS visible?

Scott,

Glad to hear you've got a wideband and are using detcans; I was worried that you were running a standard 440cc map with small injectors and no wideband when I suggested no more WOT pulls.

If I'm reading your graph correctly, it looks like you are running way too lean. Entering boost at 100kpa, I see 14 AFR and then you never get richer than 12.5 AFR under boost. NA best power is generally in the 12.5-13.2 range (some NA cars will do best torque higher in the 13.8 range) so I'm a bit surprised to see you so lean at 100kpa. On a WOT pull, I'd expect to see AFR drop right into the 12.5-13.5 range and then drop into the mid 11's under boost. Running lean under boost can sometimes make more power but that often comes at the expense of engine longevity.

Last Edit:

I'm wondering if your 125% Masterfuel tweak is correct. 440cc injectors are 110cc or 33% larger than 330cc injectors; shouldn't you bump Masterfuel to 133% instead of 125%??? 1.25 X 330cc = 412cc. 1.33 X 330cc = 439cc. 330cc injectors may be 75% the size of of 440cc models, but you need to drive 330s 33% higher to get the same flow rates, not 25%.

It does look too lean at the boost transition :( im trying to work on that ATM but i think its just the link being too slow to put my map values in and change the fueling ( ESP with a shit tune that i have ) im currently using the AFR targets in the link tuning manual.

29kpa - 14.8
60kpa - 14.7
100kpa - 14.0
140kpa - 12.5
180kpa - 11.5

Looking at the FM base maps there alot richer than this so i might have to start from scratch with that. with like you suggest 33% more fuel. luckily it doesnt really matter aslong as i start rick and use the auto tuning from there for it to lean it towards my afr targets.

I dont have a VTPS so its random, but looking at it, looks like during that period the TPS wacked out.
High is WOT
Middle is idle
Not showing is aparantly "none" so anything not WOT/idle i guess.
Sorry about all the different pic's i was hoping it would make it easier to read/diagnose. thinking about it you guys read them alot so woudlnt get as confused as i do.

I'm not wild about those AFR targets from the Link manual, they seem on the lean side. I think you would do well to change MasterFuel to 133% and then plug in the FM AFR targets for fueling. Here's a link to the FM defaults if you don't have it already:

http://www.flyinmiata.com/support/defaults.php?choice=3

Ty mate, I've done just that :) and started a retune now with fm's targets. Will put in new plugs tune then retest :) will post back soon

Ok so im still having he same issue. i loaded the fm defaults and put master fuel up ( not that i think its anything to do with this problem ). Ive put in new plugs gapped to 0.028 and still having the same issue. i back off when it happens but it feels like the car stops accelerating. Any more ideas? ive looked through and it is load dependant not rpm and ive checked that i dont have any boost overshoot protection on.

Any chance you are running out of fuel?? You can plumb in a mechanical fuel pressure gauge with enough hose to duct tape it to the windshield so you can watch your fuel pressure as you get to 6K and the power starts to fade.

Its happening in 4th and 5th aswell ( im guessing its boost related rather than rpm ) at pretty much any rpm and my A/F shows ok on logs/gage. man i hope theres not a boost protection thing im missing, ive read the tuning manual over 5 times now and still cant find anything related. its probibly a mechanical issue, but i dont know enough yet to diagnose.

What sort of wastegate/boost controller are you using?? Are you using the Link to manage boost (if so, open loop or closed loop?). What are your current boost target settings for 2500-7500 RPM? Are you using Data Log Lab to view/manipulate the Link map?

current A/F targets are done based on map / rpm

29kpa - 14.8
60kpa - 14.7
100kpa - 13
140kpa - 12.0
180kpa - 11.5

Trying to make it run richer than needed so that i get enough fuel untill my furl targets are pretty close, then ill lean it out a little.
Currently just running of wategate boost level with external wastegate with no mbc or ebc.
Yes im using DLL for maps and logging in conjunction with RTLINK. Getting a new clutch shortly so once thats in i should be able to get better logs without all the slipping. I figure aslong as i keep my foot out of it for now and make sure a/f is rich with no pinging ill be alright. basically atm im running the FM basemap with richer targets.