Boost spike problem

[40 roll]

Iv having weird boost spike back on the stock wg regardless of stock or dsp 93 tune, my mods are AEM cold air intake, 3" 02 housing, 3" catless dp and 3" catback, AGP upper and lower hard pipes, granetilli coil and wires with ngk 4306 plugs gapped@.40 right now, everything else is stock like wg, surge valve, front mount, etc...I loaded the DSP 93 tune, go do a 2-4 gear pull starting at 40mph in 2nd, when I hit it, it spikes 10 up to 4k THEN spikes 20-22 psi till 5k and tapers down to 14 at 5700-5800 where it seems to have spark cut, I datalogged and dont have an ST or LT knock but have no clue what my AFR's are at with no wideband but I added about 5-8% fuel from 3-7k to be on the safe side since iv seen people running lean on here with the dsp tune. Any clue on why it's double spiking?

I also datalogged on stock tune and it spikes 9-10 then climbs to 13 and falls back to 10 at 6k.....

[enginjoe]

That spark plug gap is too big and I wouldn't be running a tune without an AFR gauge.

[40 roll]

Quote: Originally Posted by enginjoe

That spark plug gap is too big and I wouldn't be running a tune without an AFR gauge.

well I'v been playing around with the gap to see how it runs on different setups, seems to work good on stock stock+ stock wg and stock tune with agp wg@15lbs...stop is .50 and im aware of dropping the gap with higher boost, but havnt dropped it to .35 yet which may fix the spark cut at higher rpms but im more concerned on why its not spiking 20 immediatly when I punch it and doest hit 20 until 4k rpm+. I'll get a tune at FWD performance here in a few weeks but im trying to get it running right before i take it up there.

[SRTSleeper86]

im having a similar problem with boost on the 93 tune...mine goes to ~ 14 psi and kind of hangs there then spikes over 18 psi at 4k or sometimes gradually rises over 18 psi at 4k then falls to ~ 12.8 psi at redline...

in for answers as well

[enginjoe]

It might be rich down low and can't build boost or you might have a smaller size boost leak.

[40 roll]

Quote: Originally Posted by SRTSleeper86

im having a similar problem with boost on the 93 tune...mine goes to ~ 14 psi and kind of hangs there then spikes over 18 psi at 4k or sometimes gradually rises over 18 psi at 4k then falls to ~ 12.8 psi at redline...

in for answers as well

If you find out before I do, post it and i'll do the same

[underSRTarmor]

Do a log and log these parameters send a copy to me I'll i see if I can help spot the issue.

Brandon_b_c @yahoo.com



Ambient Temperature-->
AMB TEMP--Outside Air temp

Knock control-->
KnK ST Retard--show amount of timing retarded for PCM's instant response to Knock
KNK LT Retard--show amount of timing retarded for PCM's long term or learned response to Knock. If the PCM sees a consistent amount of ST KR, it will use LT KR to try to keep ST at 0.

Spark-->
Actual Spark Cy1( you can do Cyl 2,3,4 also but there's USUALLY little difference)--Final timing advance after all modifiers.

EPDSS-->
RPM

Foundation inputs-->
MPH--Car's speed

Injector Control--->
AVG TOTAL WORKING PW The injectors final pulse width. Duty-cycle = Pulse width x RPM / 1,200,000

Throttle Sensor Input--> *More clearly IDs WOT
THR POSN---Throttle position sensor voltage-~3.6-3.9v = WOT

Map-->
AV MAP TO USE--Absolute pressure inside your intake manifold(Boost = MAP - BARO)
AV TIP TO USE--use min TIP psi as "Baro"

FUEL FLOWS--->
1/1 LONG TERM ADAP--How much your PCM is adjusting the fuel table--Usually under 15% is fine, Over 20% is borderline, more than 25% is not fine
1/1 SHORT TEM ADAP--Show instantaneous Upstream O2 sensor adjustment to fuel table
BARO-- Barometric pressure--Needed for boost calc(Boost = MAP - BARO)
TURBO TOTAL AIR PORT MASS FLOW S—actual delivered mass air flow
PRATIO ---MAP/BARO
TOTAL VE BANK1---% Volumetric Efficiency—main fuel table

COOLANT TEMP-->
ECT--Engine Coolant Temperature

CHARGE TEMP-->
ACT--Air Charge Temperature--Measured by ACT sensor in cold pipe right before throttle body

DESIRED FUEL AIR-->
OPEN LOOP FA--Commanded A/F that the PCM is trying to reach. 93tune=11.77:1. THIS IS NOT YOUR TRUE A/F!! You need a wideband to measure your actual A/F. OLFA is usually anywhere from .2 to 3 points or more different from TRUE A/F.

Torque Management-->
TRQ DESIRED--Final Desired Torque the PCM is trying to reach after ALL modifiers applied
TURBO TOTAL TRQ DESIRED = Desired Torque table value (TURBO TRQ POTENTIAL STP) minus most, but not all of the PCM's Torque limits on ECT/Gear/MPH/RPM ect.

Wastegate Control-->
TURBO WG DC--Final WG solenoid duty cycle
TURBO TRQ POTENTIAL STP--Desired Torque value from DT table BEFORE and modifiers. Changing "Boost" on your DSP will change this value
TURBO TOTAL AF DES FILTD--Airflow calculation used to determine what row of the WG DC table to use
TURBO AF ERR—g/s Difference in TURBO TOTAL AF DES vs TURBO TOTAL AIR PORT MASS FLOW
TURBO WG RPM TERM----Actual Wg DC% from your PCM WG DC table
TURBO WG ACT TERM---PCM WG DC % change based on ACT temp
TURBO WG AMB TERM---PCM WG DC % change based on Ambient temp
TURBO WG BARO TERM---PCM WG DC % change based on Baro
TURBO WG BASE---Base WG DC% = RPM TERM +ACT + AMB + Baro

[40 roll]

sent you a data log, let me know what you think!

[burks]

I wouldn't be using the 93 tune without a AFR gauge to monitor. Who knows what the hell you're at.....

[underSRTarmor]

Ur turbo is spooling slow huh???

What sensors you got 2.5 or 3 bar?

What stage PCM?

[40 roll]

Quote: Originally Posted by underSRTarmor

Ur turbo is spooling slow huh???

What sensors you got 2.5 or 3 bar?

What stage PCM?

Ya but only with the stock wg, when I had the AGP WG on it would spike instantly when I floored it to whatever I had it set to and held it well. Went back to stock wg on PCM because I bought a dsp but boost doesn't come on fast at all like the agp. I'm on factory sensors I think, don't know what previous owner did. And stock PCM running a modified stock tune with 50% increAse in boost from 2-7k.

[underSRTarmor]

why dont you get a wide band and load the diablo tune or 93 octance not sure what they call it anymore..

you sure you dont have 3 bar sensor? i see your map boost at highest 42 hmmm...i helped another guy out he had all the stock sensors they would only read up to 32.8
what is the part number on your map sensor?

your cutting out bc you running out of injector.. according to you log your would be 130 %(pulsewidth x rpm/1200000) if you could be that high i hear that 93% is pcm max....
that or the pcm is dumping fuel.. not sure.. i cant see your timing you didnt log it.. i cant read these thing that good. just alil... but you injector pulse per rpm is off the chartz


here is you boost..did you miss shift 2nd to 3rd? shifted early for sure

[asd_srt]

I had the same problem last night it spiked to about 20psi then falls to about 16 and just stays there.

[40 roll]

Quote: Originally Posted by underSRTarmor

why dont you get a wide band and load the diablo tune or 93 octance not sure what they call it anymore..

you sure you dont have 3 bar sensor? i see your map boost at highest 42 hmmm...i helped another guy out he had all the stock sensors they would only read up to 32.8
what is the part number on your map sensor?

your cutting out bc you running out of injector.. according to you log your would be 130 %(pulsewidth x rpm/1200000) if you could be that high i hear that 93% is pcm max....
that or the pcm is dumping fuel.. not sure.. i cant see your timing you didnt log it.. i cant read these thing that good. just alil... but you injector pulse per rpm is off the chartz


here is you boost..did you miss shift 2nd to 3rd? shifted early for sure

Attachment 62449

I didn't load 93 tune because i heard it goes lean so I just modified the stock tune, I plan on going to FWDP next week for a tune so no point on spending 200$ for a wideband when I could use that for a tune and have them set the WOT AFR to mid 11 to keep it safe, but I do plan on getting a wideband in the future.

Since I bought it used Im not 100% sure what PCM or sensors it has in it but I will check to see what it is for sure when I get home. Also it doesn't cut out anymore since I switched out the granitelli coil and wires for a mopar coil and Bosch wires, lowered gap on the NGk 4306 to .35.

I'll make another log but with my lap top so I can get all the parameters logged.
I missed 4th gear only on 1 run. Check out the mph, but you see when I get back in it, it doesn't spike high at all, boost just climbs. I'm going to buy a FM wg.

[underSRTarmor]

Iirc speed was 60 but I cant remember.

Just be cafeful.


The boost is doing what the PCM is commanding. If you look at the wg dc the boost is following. Except at redline where the boost falls off the PCM is trying to give more