Excessive boost on 93 tune stock srt-4

[1srt4me]

I just used the predator U7134 with the latest revision to update my 2004 dodge srt-4. I could feel the difference right away. The problem is at wot in 4th gear my stock boost gauge will peg at 20 psi. The car has no hesitation at that point and pulls like crazy but I am worried that it may get too much boost. My car is fully stock except for a mopar bov. I am running 91 octane chevron gas. 1st gear thru 3rd it will hit about 17 to 18 psi and hold but 4th gear it will peg gauge. How much boost will the stock waste gate hold? Is there a chance of overboost? Thanks in advance for advice.

[sfla_srt4]

You are overboosting a lot.. Do you have a wideband?? If not, I suggest turning down the boost. Log the car and see what its doing. Make ure to log Knock ST and LT.

[1srt4me]

I do not have a wideband and car is entirely stock except for mopar bov. I thought the stock waste gate would not allow it to overboost? I do not have a spring mod on the WG and I am the original owner of the car. I only tried wot in 4th gear a couple of times and when the boost gauge hit 20+ the car did not have any hesitation or power loss. I will run a log and adjust the boost down...Do you think the computer needs some drive time for self-adjustments?

[28patrick28]

Well 20 psi is a lot, specialy with 91 oct gaz, Be sure to log st knock and lt and check if you have knock too (1 to 3 max is acceptable, Specialy on shift) Get a wideband to be sure to be max 11.5 to 12 afr. run 18 psi max if u dont have a new fuel pump.

U can try to remove the no. 21 fuse on the engine bay fuse box to reset the pcm, so wg duty cycle gonna relearn (But i hear that wgdc are fix with predator, Not sure yet)

[1srt4me]

Ok top end of first gear at wot 2.5 ST 0.0 LT 2nd gear wot had 6.0 ST 1.0 LT 3rd gear wot had 5.5 ST 3.0 LT 4th gear wot 4.0 ST 3.5 LT These are the highest readings that I found for each reading in each gear. So I gather these are much too high. The other gears did not go over 18 psi except for 4th that hit 20+ psi. I did not clear my pcm before I installed the 93 perf tune. I have not tried to custom tune and lower boost level. Should I try and put back my stock tune, clear pcm, then install the 93 tune again so pcm can learn from clean slate?

[sfla_srt4]

You should lower the boost, or go back to stock and record the knock. What type of gas are you using?? Maybe try a diferent brand of gas. That is too much knock though..

[1srt4me]

I use Chevron gas at 91 octane. There is a place out here that sells street blaze gas that is 101 octane I believe and it is also around $7.50 a gallon for it. I thought that the 93 perfomance tune could be used with 91 octane. I have heard that octane boosters do not work very well. I will try to lower the boost settings tommorow and see if that helps. I assume Chevron gas is good gas and I never use ARCO. How high will the stock wga allow boost to climb?

[Quick]

Arco might be better than Chevron (it is here). Arco is owned by BP.
In CA they're allowed to get their gas from someone else's refinery. Mobile for example. Mobile only has a refinery in Southern CA so in the North Bay area they get their gas from someone else's refinery. The only difference is the additive packages that they add when it goes into the tanker truck for delivery.

[1srt4me]

I was not sure how much to lower the boost in each range so I went 5%. I will run another data log and see if the knock decreases and boost lowers. Is the 93 octane tune supposed to hit such high boost? The boost holds at 18 psi in third gear and pegs the boost gauge on 4th gear. I would see 15psi max before tune. I really need to get a wideband.

[sfla_srt4]

Its not supposed to hold that much on a stock setup.. Maybe spike the 18 and hold 15.. Are you sure your stock??

And YES, you need to get a wideband..

[1srt4me]

Yeah it is 100% stock except for a mopar bov which is pretty much just a noise maker. I was thinking maybe I should have cleared the pcm before updating with the 93 octane tune....then it could re-learn with the new settings. I purchased this car brand new from the dealer so I know for sure that it is stock. I don't even have a cold air intake just a drop-in K&N filter. All I know is when the stock boost gauge was pinned at 20 psi I got scared. I don't want to blow up my motor.

[sfla_srt4]

Get a wideband, and you will be fine.. Its amazing the car is actually holding that amount of boost, stock.. The car should have "learned" by now and brought back the boost a little to what it wants to see. You could go ahead and just take the negative off the battery to reset the PCM and see what that does.

[1srt4me]

After I lowered the boost 5% in every range I now hit 13 to 14 psi first gear wot second gear will hit about 17 psi and then drop to 15 psi wot and third gear will hit 19 psi and drop to 18 psi wot but fourth will hit 18 psi and climb to 20 psi. It seems it did make a change to the boost levels. I did not data log this was a run on the way home from work so I don't know what the knock rate was. Car felt great and had no loss of power. I don't understand why the boost is not only holding in fourth but it actually climbs!! How much more do you think I should lower the boost and in what ranges. If I could get a max 16 to 17 psi I would feel better.

[sfla_srt4]

Get a wideband to see your AFRs.. Your boost is good there, just worry about knock and AFRs. You may wanna drop the boost a bit more though, just to be safe for now. Lower the boost more in the upper ranges, like 3-4ish and up.

I just cant believe that a stock car would hold this much though.. The COT feature would cut in and limit the boost and make the AFRs nasty rich in the higher gears. Post up a log, I would like to see this.

[1srt4me]

Obiviously when I run the log I should monitor ST & LT knock, RPM, Throttle Position...any other sensors I need to record?