chief34 Posted February 4, 2009 Report Share Posted February 4, 2009 We have the Mpi finished and it is running pretty damn good BUT.... It has - Fully built motor, with Fully ported head yada, ,yada ... (Everything literally possible you can buy for it...) - 750cc Trilogy injectors... - Magna intake....... - Haltech ECU......... (fuel only) - T-70 Turbo - 3" exhaust - Giant intercooler... Right now I have it tuned to right at 14 psi and it seems to be running really good.... The goal is 25-26psi. Here is my first question.... How the "F" does the stock boost gauge work? I have searched and searched and cant find any info on it.... It worked before the install. We must be missing something. We are running a map sensor, is there something that is missing for the stock gauge? like maybe the boost solonoid that used to be there with the air filter, or??? I hope somone knows lol ... Secondly, We are running the fuel with the haltech and using the stock ignition for timing. I am a little worried about timing... Is this going to be ok? I know folks do it but I am wondering if it can pull enough timing under boost since the stock car was only made to run 10.5 psi.... So what happens at 20 or 25 psi?? Do we have to upgrade to DIS in order to go more than 14 psi? I appreciate any help guys!! We cant wait to get this thing to the dyno Gotta get this timing stuff straightened out..... Link to comment Share on other sites More sharing options...
eurotiva Posted February 4, 2009 Report Share Posted February 4, 2009 Only advice I can give is not to trust the stock gauge too much. Sorry. Link to comment Share on other sites More sharing options...
shoquest2007 Posted February 4, 2009 Report Share Posted February 4, 2009 First answer is the boost gauge is controlled by the computer that you took out. its electronically controlled through the stock computer. so you would have to replace it with an aftermarket gauge. As far as timing goes, i know people run stock ignition on 18 and 20 psi, but your best answer will come from someone else who can answer that to a better degree. Link to comment Share on other sites More sharing options...
chief34 Posted February 4, 2009 Author Report Share Posted February 4, 2009 (edited) Ok sorry, but there is a little confusion here. The haltech is running the Fuel only. The stock computer is running the timing through the Distributer and the igniter. We are using an aftermarket boost gauge for tuning purposes, but I am worried that the igniter is not working correctly due to the stock gauge not being hooked up correctly. Plus since the car is only limited to 14 psi right now it would be nice to use the stock gauge for now.... Does anyone have First hand knowledge of this little problem right here? I scared to up the boost to 20 without knowing.... It seems to be getting touchy to tune above 14 psi. I have a feeling it is timing related.... By the way, I'll get some pics on here real soon, because I know there is probably some people who want a visual.... Edited February 4, 2009 by chief34 Link to comment Share on other sites More sharing options...
JamesR Posted February 4, 2009 Report Share Posted February 4, 2009 Ok sorry, but there is a little confusion here. The haltech is running the Fuel only. The stock computer is running the timing through the Distributer and the igniter. We are using an aftermarket boost gauge for tuning purposes, but I am worried that the igniter is not working correctly due to the stock gauge not being hooked up correctly. Plus since the car is only limited to 14 psi right now it would be nice to use the stock gauge for now.... Does anyone have First hand knowledge of this little problem right here? I scared to up the boost to 20 without knowing.... It seems to be getting touchy to tune above 14 psi. I have a feeling it is timing related.... By the way, I'll get some pics on here real soon, because I know there is probably some people who want a visual.... The stock gauge has nothing to do with the ignitor. Just REMOVE the stock gauge and replace it with an aftermarket gauge. I've also been running a MPI with the stock ignition for over 5 years now. Link to comment Share on other sites More sharing options...
chief34 Posted February 4, 2009 Author Report Share Posted February 4, 2009 (edited) Ok , thats kind of what I figured with the gauge.... So the only other thing is, what kind of boost are you running? This car seems to be running great at 14 psi..... The only thing right now is the vaccum advance on the dizzy is hooked up to a full vaccum port on the magna intake and is making the idle waaay advanced like 36 degrees or something..... So we are going to hook up the VA line before the throttle body so it wont see any vaccum at idle but it will see some at part throttle and light loads. Also under boost it will still retard. Is this how you have yours? By the way, thanks for the replies guys... Edited February 4, 2009 by chief34 Link to comment Share on other sites More sharing options...
Technology Posted February 4, 2009 Report Share Posted February 4, 2009 That's how it is stock, no vacuum at idle, but under normal driving vacuum, it will work as it should. As for max timing, you will have to feel that out and adjust the distributor to change it. The stock boost gauge never read accurately from the factory. You need a real one to really read the boost. Link to comment Share on other sites More sharing options...
chief34 Posted February 4, 2009 Author Report Share Posted February 4, 2009 I really appreciate the replies guys.... Let me just get this staright with everyone for the last time.........I understand that the stock gauge isnt perfect. We are using a mechanical gauge to tune the car. For now we want to keep it clean and stock looking inside. It would be nice to have the stock gauge working right now because its only pushing 14 psi. If ANYONE actually knows why this wouldnt be getting signal and what it uses to make its calculations, I would love to hear from them. Also, if there is anyone out there that is actually pushing 20+ psi and using stock ignition I would love some imput from them as well. It seems that the 500 hp guys are like phantoms when it comes time to ask for help. This car should be making 500 plus eventually... Does anyone actually know how many maximum degrees of retard the dizzy can pull under boost? " Technology" ... I know thats how timing is supposed to work on the stock car, thats exactly why I am going to route it that way.... The only difference will be that at part throttle and cruising the timing is probably going to be more advanced than the stock timing would be because this car pulls major vaccum and its not gonna be through a ported vaccum port. I still dont think that will be an issue because its only during part throttle and cruise. Again thanks for the replies, I Know everyones trying to help.... Its so hard to find actual specifications for these cars, lol.... Its like its classified or something :character0285: -Tim Link to comment Share on other sites More sharing options...
Technology Posted February 4, 2009 Report Share Posted February 4, 2009 Well, MPI changes everything. with my cam and TBI, I was down to 18 inches of vacuum, and stock cam was like 20-22 sometimes. Now with the MPI it's back up a little more, as I recall. I haven't had my MPI running for very long. And I blew the engine with too much timing, so be very carefull. Max stock timing is like 30 degrees I think, but that's with the vacuum advance. Under boost, it will go down. I don't know for sure, but I would imagine it's not much more than 15 degrees. I was at or above 17 degrees and it cracked my block and ring lands on #4. And I have a 61mm garrett. You might be able to use the stock boost gauge just for fun. Put your stock mass air sensor back on in front of the turbo. It has to be plugged in, and the stock ecu has to be plugged in. It won't affect anything because timing and fuel are independently controlled in stock form. And you have aftermarket fuel control. Just make sure the B38 plug is plugged in. It should be right now if the car runs and your gauges work. Guys with 500hp are not using stock style ignition. If they are using the distributor, it has been locked and advance is controlled with an aftermarket ecu. Link to comment Share on other sites More sharing options...
chief34 Posted February 4, 2009 Author Report Share Posted February 4, 2009 Thats very helpfull! When you blew your engine where you monitoring AFR? How did you end up figuring out you were at or above 17 degrees? I think we are at the limit , or close to it, with the stock ignition because it seems to getting really hard to tune above 14 psi. I dont hear any knocking but I cant rule that out.... It seems like it starts cutting out and The AFR gets rich but if I try to lean it out a TINY bit I tries to pop and go like 13:1 .... So it seems like its gonna need EDIS to go higher or maybe some more Octane. 91 and octane booster might not be cutting it... Right now limited to 14 psi it seems to run really good. Full potential I am not quite sure, but it runs hard. To me it sort of seems like it should have more bottom end but maybe thats due to the huge turbo and 3" exhaust..... When the boost finally gets to full boost (at about 3500rpm) it starts to pull really good and hard all the way to about 6500 rpm....... I guess its time to get it to the dyno! Link to comment Share on other sites More sharing options...
Technology Posted February 4, 2009 Report Share Posted February 4, 2009 I have an AEM EMS that I use for tuning. It has the ability to control all aspects of the engine from timing to fuel, it accounts for knock (if the sensor had been working), and AFR's from my wideband And yes, I was monitering them, and it was reading like 11.5. I wasn't logging though, which I really should have been. Do you have a stock cam? Also, ignition timing can have a lot to do with how/when the turbo spools. That and wastegate control. Link to comment Share on other sites More sharing options...
chief34 Posted February 5, 2009 Author Report Share Posted February 5, 2009 Well it has a TEP cam in it.... I'm kind of at a crossroad now I guess without being able to moniter or control timing. I think were gonna get it to the dyno soon here to see what its got at 14psi... Link to comment Share on other sites More sharing options...
Indiana Posted February 5, 2009 Report Share Posted February 5, 2009 The stock distributor you set up for base timing at 10btdc The mechanical limit of the stock distributor is 34 degrees about 5500-6000rpms The referenced boost ignition retard from the vacuum advance unit is about 7 degrees max, its physically limited from hitting the distributor body and since stock boost was so low there was no need for it to go any further. 10+34-7=37 total timing You can not have the reference hose for the distributor INSIDE of the plenum, you will get what you observe, timing advance at idle. You need to have it right at the throttleplate but not inside. You can see the opening on the stock throttlebody its a tiny hole and as soon as you crack the throttleplate open it gets to see the vacuum from the intake. You can move the reference hose to the intercooler plumbing as near as possible to the throttleplate if your throttlebody has no port for that and if the boost goes really high I'd also re-think your base timing and set that perhaps around 5 to 7btdc. The stock boost gauge (87-89) uses the MAS and some math inside the ecu nobody really knows, or cares to come up with its best guess but its only for the gauge forget it, on the cars that had a map for a boost reference they worked using that signal. You can use an air fuel gauge sure but that won't tell you anything about timing, EGTs, spark plug heat range you have to monitor all that yourself and go very slowly and watch all of those things closely. Link to comment Share on other sites More sharing options...
autoxer Posted February 5, 2009 Report Share Posted February 5, 2009 I drilled a hole slightly smaller than a piece of 3/16" brake line in the bottom of my throttle body like a 1/8" in front where the throttle plate is when closed and drove a 3" long piece of 3/16" brake line into that hole, this is what I am using for a ported vacuum source. Because its just in front of the throttle plate it sees little to no vacuum until you crack the throttle. seems to be working I have no timing advance at idle but unsure how much retard I am getting but I dont think It's the full 7 degrees but its working. Link to comment Share on other sites More sharing options...
chief34 Posted February 6, 2009 Author Report Share Posted February 6, 2009 Thanks to both of you and especially to indiana! Thats exactly what kind of info I was wondering about. Stock boost gauge is getting ditched and we already tapped the intake tube in front of the throttle body to fix the timing advance reference.... Its definately a complain not being able to control timing. Thats gonna have to get changed for sure. At least you confirmed what I was thinking and that is that the retard isnt enough for real high boost.... Thanks for all the info! -Tim Link to comment Share on other sites More sharing options...
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