I think you are right i have notoced the same sort of things with my testing so far. If i boost to a pretty high number the pcm tries to pull it back, and if it can't I hit fuel cut! as for the temp mod i did a adjustable pot parelel with the hot sensor and adjusted it down but going to far made the ecu richen the engine back up!
Quote: Originally Posted by BlackWrath
Quote: Originally Posted by westrock
If the PCM goes into open mode when WOT, it will never know the air fuel ratios either before or after.
Boost controllers, aftermarket WGA and mapclamps all do the same thing. They allow more boost to go into the engine than the PCM would allow. The engine may not pull timing with those, but pulling timing does not hurt a motor. However I don't know if any manufacture on here shows what the timing is doing with there product despite the gains in power. At this point we don't even know that timing is being pulled at all...it may just wait for a knock signal before it starts.
It may get higher AFR's on the highway, because due to the increased rolling resistance and air friction there will be more load on the turbo and possibly (slightly) more boost as a result. I don't see how that would be any different than any of the other parts I listed above.
Also this was on a totally stock Stage 0 car. If you get any of the stage upgrades or a fuel line return kit which many poeple do you will get increased fuel flow, thus a safer margin. Also this "mod" is adjustable so you can raise the values to make it a little richer.
I'm not trying to tell you guys that the other forms of boost regulators suck, I'm just giving you more options. I made that clear in the beginning.
I appreciate your experiment! Here's some info I've gathered over the last two years or so that may help out. I've been datalogging this car since the day I picked it up, so here is my $.02 on the subject....
As per your post in the quote, the car DOES lower timing with increased boost. On a hot day at 15-16 PSI dropping to 12 my timing goes from 18* to 26* at redline. On a cold day with bost from 14 to 11@ redline the timing was 22* to 30*. With the boost set to 17PSI dropping to 15@ redline timing is 16* to 20*. The first two were on a consistant basis with the stock wastegate and unmodified car. The higher boost results were documented after the PCM had time to adjust to the changes (modified stock wastegate).
When I get spark knock, the timing goes from the mid 20's to low teens sharply. There is a big difference in pulling timing from high boost and pulling timing from knock on the graphs. Sometimes it gives the timing back quickly and somtimes it doesn't, depending on the serverity. Also, when the MAP is maxed out (above 18PSI) over 4500 RPM, it pulls timing fast, and tries to get boost under control. This is usually why the boost goes back to normal with a modified WG using the stock WG seloniod after a few 4th gear pulls.
I have one question about your temp changes......was the MAP clamped when you did the temp sensor change? IMHO, if you didn't, then the MAP would over-ride that by being maxed out and dropping boost and/or timing to get it back into control, regardless of intake temp.
Umm guys seriously.... I think most of you need to learn the difference between cold air intake (CAI) and fender well intake (FWI). Most of the intakes you guys are talking about (even the topic starter) are fender well intakes. Cold air intakes (CAI) are the ones with the boxes and the filter sits in the engine bay behind the headlight.
Quote: Originally Posted by SRT-4Sleeper
I'm looking for a high flow Tstat.
Also, previous owner said he fixed it so that oil dosn't get pushed through the intercooler. So that means I don't need a catch can right ? This is my first turbo car, previous car was supercharged so I'm learning right now. Be nice
[Edit] Nevermind.....I'll try to be nice instead.
__________________
'04 SRT4- 12.4@112
'86 Grand National - 10.22@129
'01 Dakota 4.7
Last edited by BlackWrath : 08-28-2006 at 03:47 PM.
WOW! I just read this entire thread because i was absolutely SHOCKED by that Graph! This is EXACTLY what my car feels like...pulls very hard as soon as it spools then falls off HARD! I don't mean in anyway to hijack this thread but check out mine if you think you can help me... .50 Trim Help Please?
I was just so shocked to see a graph like that, it paint a perfect picture of what my car is doing and i'm DYING to figure out how to fix it! Good job with the research BTW West!
I played around with this using 2 POTs and have the say the difference in power is defiinately there. I only had it on for a couple of pulls, so I don't know if the computer relearns anything or throws a code, but I got it to raise 3 psi and it breaks the tires loose pretty easily.
As per your post in the quote, the car DOES lower timing with increased boost. On a hot day at 15-16 PSI dropping to 12 my timing goes from 18* to 26* at redline. On a cold day with bost from 14 to 11@ redline the timing was 22* to 30*. With the boost set to 17PSI dropping to 15@ redline timing is 16* to 20*. The first two were on a consistant basis with the stock wastegate and unmodified car. The higher boost results were documented after the PCM had time to adjust to the changes (modified stock wastegate).
I wanted to comment about this as it pertains to what I'm doing know. I have long since abandoned the stock turbo, however I still have kept this mod to a certain degree.
Since I went to the 50 Trim and 750cc injectors I had to use a DTEC to trim the MAP signal back. Many poeple have said that as a result of artificially lowering the MAP signal the PCM will raise the timing. Now on a larger turbo this can be problematic because we are actually running more boost which means more pressure in the cylinders, then you add more timing which adds even more pressure.
So as a result I went ahead and put a resistor in the IAT that should make the PCM think that its always about 150*F. My hope (as is quoted above) is that the PCM will back off on the timing and counter act the advanced timing from trimming the MAP signal.
It seems like a good idea for those of us running bigger turbo's with piggybacks instead of full standalones. I have not thrown any CEL related to IAT sensors...just the normal big turbo CEL's. I think like P0111 is a IAT one that some poeple get when the IAT is disconnected or something??
Oh and the torque curve on my 50 trim is rediculously smooth now...so
__________________
-David
06 Lotus Exige
280HP Supercharged 1.8L 05 Black SRT-4 (sold) 330HP & 307TQ @17 PSI (mods in pic)
If you set an error code because the ecu dosent like the readings from a sensor then it quits listing to that sensor and quit commonly goes to open loop and some times limp mode. So the temp resister mod could be a waste of time or even hurting your performance.
on your intake temp mod, i didnt see any pics on showing me which sensors to look for and what wires to tap into, i looked on how to and all that and was gonna give it a try.
Garrett
Your message box was full.....I updated it.
And for below.....
Quote: Originally Posted by srt4does13s
it would help if you labeled the proper sensors. the sensor you have showing as the tps, is your iac ( idel air control)
Thank you for pointing that out, I only labeled it for location familiarization. And not that it makes any difference since I wasn't using that part.
Quote:
it just seems to unstable... your dyno with that resistor is all over the charts
I would exactly call the first dyno run one with IAT sensor plugged in stable either.
Heres the proof as to what happens when you increase the intake temps that the PCM thinks it sees. Tests were done using 3.91K ohms at the firewall and 3.32K ohms at the throttlebody. This gives the PCM the idea that the air heats up a little as it goes through the system, which is realistic.
Tests were performed in 70*F which is a good "practical" temperature. Lower temperatures will probably provide more power and higher temps will provide less power.
Whats it do?. There has been much speculation that the SRT-4 PCM will increase boost at higher temperatures to make up for the fact that hot air is less dense (less air in a given volume) thus less potential for horsepower. Because our PCM shoots for a horsepower goal, it increases the boost at higher temps to make up for the less dense air. So during the summer you may see boost levels of say 14-15, but during the winter maybe only 11-12 PSI.
On most cars this wouldn't be that big of a deal, because most cars manage their fuel a little better. Our cars however run pig rich, and this is what I wanted to test. Because the PCM would see a very high intake temp it would increase the boost pressure by several PSI, but would most likely not increase the fuel at all. So the question was, did the car run rich enough that the extra air could offset the fuel and make more power while keeping safe air fuel ratios.
Why do this? Basically this is doing the same thing as all the other boost "mods" out there. It increases the boost a couple PSI, just like a boost controller or a WGA or the other "ghetto" mods. The difference is that the PCM is doing the boosting here, so partial throttle boost stays the same and the PCM is happy without the need for map clamps. It requires two resistors which will probably cost somewhere between $0.20 and $2 depending on if you can buy individual or packs. It also takes a matter of minutes to do this.
Anything to worry about? Yes. As I had seen when I first attempted this, the PCM lets the wastegate close very liberally at first. Which means on a stock turbo at 3-3.5K RPM you can hit 25 PSI for a split second very easily. If you ease the throttle on instead of mashing it, the turbo behaves a little better. As a result you run very lean for that small amount of time. Its not on the dyno chart below but I saw something like 17 A/F Ratio, but then dropped down to 12 across the board. This could be remedied by trying higher resistence resisters (lower simulated temps)....though it will affect the overall boost schedule. But there may be a good balance point.
So this might be a great mod for Stage 3 (which I will also dyno after I install Stage 3) because S3 also runs pig rich and the turbo is slightly bigger so the wastegate may be able to control it better. Using 2.5K resistors at both ends I was able to maintain 17 PSI all the way out...so that may be a good option for using a 50 trim on say Stage 2 and keeping full PCM drivability.
Anyways I'm sure your ready for the dyno results. Only mods are 3" BDJ's CAI, BDJ's FMIC, and the very back section of the stock exhaust removed (opens right behind rear axle). Basically mods that really shouldn't have any real benefit on a Stage 0 & stock turbo on a dyno.
As you can see....almost 250HP on a S0 car with almost no mods. The torque kept getting false readings towards the end, so that is why the torque is cut off on the base run. These runs were done 5 minutes apart. We ran baseline, turned off motor, I installed resistors, turned on car and ran 2nd dyno.
With Stage 2 to provide extra fuel and a 3" exhaust, this would probably be pretty good.
How To Do This
Take the resistor and bend the legs over so make them twice as thick. This way there will be more "bite" when you plug it into the harness. Unplug the harness from the stock IAT sensor inside the charge pipe. Now insert the resistor into the harness, pushing it in securely. You could put tape around it or cover it somehow. I just ziptied the harness to the TPS harness and let it be. I don't drive in the rain often and its been fine so far (like 6 months now).
it would help if you labeled the proper sensors. the sensor you have showing as the tps, is your iac ( idel air control) and yes you did make more whp in your mid rpm range, but then you lost more whp in the upper prm range than you did with stock settings, then gained about 10 whp... it just seems to unstable... your dyno with that resistor is all over the charts.
Last edited by srt4does13s : 01-09-2007 at 03:23 AM.
Heres the proof as to what happens when you increase the intake temps that the PCM thinks it sees. Tests were done using 3.91K ohms at the firewall and 3.32K ohms at the throttlebody. This gives the PCM the idea that the air heats up a little as it goes through the system, which is realistic.
Tests were performed in 70*F which is a good "practical" temperature. Lower temperatures will probably provide more power and higher temps will provide less power.
Whats it do?. There has been much speculation that the SRT-4 PCM will increase boost at higher temperatures to make up for the fact that hot air is less dense (less air in a given volume) thus less potential for horsepower. Because our PCM shoots for a horsepower goal, it increases the boost at higher temps to make up for the less dense air. So during the summer you may see boost levels of say 14-15, but during the winter maybe only 11-12 PSI.
On most cars this wouldn't be that big of a deal, because most cars manage their fuel a little better. Our cars however run pig rich, and this is what I wanted to test. Because the PCM would see a very high intake temp it would increase the boost pressure by several PSI, but would most likely not increase the fuel at all. So the question was, did the car run rich enough that the extra air could offset the fuel and make more power while keeping safe air fuel ratios.
Why do this? Basically this is doing the same thing as all the other boost "mods" out there. It increases the boost a couple PSI, just like a boost controller or a WGA or the other "ghetto" mods. The difference is that the PCM is doing the boosting here, so partial throttle boost stays the same and the PCM is happy without the need for map clamps. It requires two resistors which will probably cost somewhere between $0.20 and $2 depending on if you can buy individual or packs. It also takes a matter of minutes to do this.
Anything to worry about? Yes. As I had seen when I first attempted this, the PCM lets the wastegate close very liberally at first. Which means on a stock turbo at 3-3.5K RPM you can hit 25 PSI for a split second very easily. If you ease the throttle on instead of mashing it, the turbo behaves a little better. As a result you run very lean for that small amount of time. Its not on the dyno chart below but I saw something like 17 A/F Ratio, but then dropped down to 12 across the board. This could be remedied by trying higher resistence resisters (lower simulated temps)....though it will affect the overall boost schedule. But there may be a good balance point.
So this might be a great mod for Stage 3 (which I will also dyno after I install Stage 3) because S3 also runs pig rich and the turbo is slightly bigger so the wastegate may be able to control it better. Using 2.5K resistors at both ends I was able to maintain 17 PSI all the way out...so that may be a good option for using a 50 trim on say Stage 2 and keeping full PCM drivability.
Anyways I'm sure your ready for the dyno results. Only mods are 3" BDJ's CAI, BDJ's FMIC, and the very back section of the stock exhaust removed (opens right behind rear axle). Basically mods that really shouldn't have any real benefit on a Stage 0 & stock turbo on a dyno.
As you can see....almost 250HP on a S0 car with almost no mods. The torque kept getting false readings towards the end, so that is why the torque is cut off on the base run. These runs were done 5 minutes apart. We ran baseline, turned off motor, I installed resistors, turned on car and ran 2nd dyno.
With Stage 2 to provide extra fuel and a 3" exhaust, this would probably be pretty good.
How To Do This
Take the resistor and bend the legs over so make them twice as thick. This way there will be more "bite" when you plug it into the harness. Unplug the harness from the stock IAT sensor inside the charge pipe. Now insert the resistor into the harness, pushing it in securely. You could put tape around it or cover it somehow. I just ziptied the harness to the TPS harness and let it be. I don't drive in the rain often and its been fine so far (like 6 months now).
it would help if you labeled the proper sensors. the sensor you have showing as the tps, is your iac ( idel air control) and yes you did make more whp in your mid rpm range, but then you lost more whp in the upper prm range than you did with stock settings, then gained about 10 whp... it just seems to unstable... your dyno with that resistor is all over the charts.
wow, i just read this whole thread and i was thinking bout what dan said, "the pcm quickly learns and pulls back" but both before and after graphs have a really close shape with just more power with this mod, and if the comp is learning then theres something wrong with this west's iat sensor for it to act like that. so in essence i think that if possible he should leave the mod on for a few weeks to let the comp have time to learn and run another dyno and compare that to the other graphs, so if its the same, then this is good, but it will only work with pcm controlled boost.
one thing i dont get is some people have posted that the comp will pull timing and that will promote knock, but why would it do that when if you run 30psi on a stock motor the comp will yank timing and prevent that knock you would get with 30psi and no fuel.......
what will this mod do with my mods....please let me know.
__________________
273 HP 315 lb TQ @ 20 psi and 13.2@103mph before/ now fully built mammoth combo,map clamp,ptp 75-80 fpr mod and mpx 3'' o2 housing and RFL blow off 325hp 444tq
what will this mod do with my mods....please let me know.
are you on pcm control????
if so, maybe 20whp i'd presume.....but if your boosting all you can for your supporting mods this wouldn't be useful....this is the poor man's boost controller. if you have any sort of boost controller, this would be pointless
__________________
Quote: Originally Posted by killaneon
boogaloo is always good for a lulz
"i need you, like a little boy's salad needs some neverland ranch"
......SRT-4.....the domestic with an identity crisis.......
Stage2 @ 20psi + bolt-ons out the @55 my quest for 250mph in the quarter mile
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
my quest for 250mph in the quarter mile
Linear Mode
