EZ-E Posted January 15, 2005 Share Posted January 15, 2005 Just a curious thing, I was thinking of how to get my best run at the track, looking at the transmission calculator and with what I have in my car, using a redline of 5500 rpms, I should be shifting as follows 1 = 30 2 = 50 3 = 80 4 = 106 I have an 82 Turbo, stock electronics, 370cc injectors, AFPR (currently set at 38 psi static), walbro 255 gph fuel pump, intercooler, boost at 15#'s, it has the borg T-5, and a 3.7 LSD, with 225 50 15 rubber. Well on a lone stretch of road I decided to test the calculator. I got to about 65 and all was still well till I hit 70 and the AF meter started going from rich to mental flapping from lean to rich, in a very strange matter, was extremely erratic. Anyway I get home, pull the plugs, they are as expected very clean and white. Now usually I dont go above 5k, but figured maybe that little more would help. Does it always happen like this no matter what you do, as long as you have stock computer and electronics will it just lean out at 5k+ rpms? Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted January 16, 2005 Share Posted January 16, 2005 hmm... with everything you have.. it shouldn't lean out.. especially with those bigger injectors and the AFPR... hmmm... maybe it's just the limit of the stock turbo ECU... I am interested in this to... anyone have a good answer? Quote Link to comment Share on other sites More sharing options...
Clifton Posted January 16, 2005 Share Posted January 16, 2005 Anyway I get home' date=' pull the plugs, they are as expected very clean and white. Now usually I dont go above 5k, but figured maybe that little more would help. Does it always happen like this no matter what you do, as long as you have stock computer and electronics will it just lean out at 5k+ rpms?[/quote'] If you drive a while after your WOT run then the plugs won't read as they would if you pulled them right away. I would only trust a wide band though. If you are running 370's you also should have plenty of fuel for a stock turbo. The AFPR isn't helping or hurting as it's so close to the stock pressure. I don't know why you don't go above 5K, is it a fear of running lean? You should be making power to 6.5K. If it was leaning out I would check the pump pressure at full boost at max RPM. Quote Link to comment Share on other sites More sharing options...
EZ-E Posted January 16, 2005 Author Share Posted January 16, 2005 I mean Im one not to trust fuel running into the cabin of the vehicle. I didnt check the plugs straight away, as it was about still 3 miles to my house from where I made the run. The plugs are a colder BPR7ES plugs as well. What I dont get is that with the 370cc injectors at 15#'s of boost I should be at 52#'s of pressure at full boost, and I just cant see how it would be going lean. I have one of Pallnets fuel rails, maybe I could run a line off of that from where the pressure gauge on the rail is outside of the hood, so I could look at it. I know that the electrical is well and Im not losing any power for it to drop pressure, amperage is at 13.6, so no loss there. Thing is I have a digital dash, not the analog dash so its hard to tell where Im at above 5k rpms because of that digital dash, so I was going to use the mileage for shift points. Could the tranny calculator be off, and Im going higher then where i should be in the scale of mph vs rpms? Thanks for your suggestions guys. Quote Link to comment Share on other sites More sharing options...
TimZ Posted January 16, 2005 Share Posted January 16, 2005 I mean Im one not to trust fuel running into the cabin of the vehicle. I didnt check the plugs straight away, as it was about still 3 miles to my house from where I made the run. If you want a permanent gauge, they do make electrical gauges for this. If it's just a spot check, I usually tape a gauge to the outside of my windshield. Looks kinda stupid, but I'm not gonna burn to death, either. Have you done anything with the AFM? If you have not adjusted the spring pressure, you are probably just maxing it out. Your injector pulsewidths will most likely remain the same after that point. Quote Link to comment Share on other sites More sharing options...
Len Posted January 17, 2005 Share Posted January 17, 2005 EZ-E I run 15psi also...could go a bit higher in winter...another option is if you have an AFPR set it at say 42 or 44 psi at idle with vacume removed and plugged. That way you can possibly max out your injectors a bit more 59psi. Also as Tim mentioned play with you AFM a bit mark where it was. Then tighten it a bit them see what happens...tough without a WB to know for sure (I don't have one either). I have run a mechanical fuel pressure guage with a long fuel injection fuel line in my cab for tuning purposes to really see press at boost. Scottymiz ran 17/18 psi with our setup...he also blew up his engine . 15psi should be OK. I should write a disclamer for that last statement Quote Link to comment Share on other sites More sharing options...
TimZ Posted January 17, 2005 Share Posted January 17, 2005 I should mention that tightening the spring in the AFM will make the car run uniformly lean. You then have to comnpensate for this by increasing the fuel pressure. Quote Link to comment Share on other sites More sharing options...
Len Posted January 17, 2005 Share Posted January 17, 2005 Your right Tim but with these 370's usally we have a rich condition until we start going wot then the force of the air thru the flap will open fully wide anyway since the afm's were developed for 7 psi and we are boldly going were old z's have never gone before... to 15 plus psi and beyond.. I hear what your saying with reference to EZ-E's situation contrary to what his problem is (lean at wot) but hey this helps getting there! BTW Frank Zappa is my hero! "I am what I am cow's don't make ham!" Quote Link to comment Share on other sites More sharing options...
TimZ Posted January 17, 2005 Share Posted January 17, 2005 BTW Frank Zappa is my hero! "I am what I am cow's don't make ham!" Mine too Quote Link to comment Share on other sites More sharing options...
EZ-E Posted January 17, 2005 Author Share Posted January 17, 2005 I have adjusted the afm to 19 ticks tighter for the car to run well and still just a tad rich at idle. It idles well though and I never had any problems, like you all said I could just bump up the pressure when I want to go to the track as well. Just seems weird that with what I have that it would go that lean. Its been very and I mean very cold here as of late, so Ill have to wait to test again as it the temperature is well into the - single digit right now lol. Well we will wait and see what happens, Im just wondering if I went further then 6500rpms. Concidering with the digital dash it is really hard after 5k rpms to see where your at in reality. Curious to see what the fuel pressure is and Tim i like your idea, it may look silly but there is nothing wrong with that, like you said im not wanting to catch on fire lol. Thanks for the suggestions, when the weather gets a bit better, Ill let you know what i get. Quote Link to comment Share on other sites More sharing options...
wheelman Posted January 18, 2005 Share Posted January 18, 2005 Is it possible that the fuel lines aren't able to flow enough fuel at higher RPMS even with the higher FP? I'm swapping an LT1 into my Z and was forced to upgrade the fuel lines to 3/8" feed and return in order to flow enough. I didn't need to use 3/8" on the return, the rail has 5/16" attached but it was easier to use the same size for both. Just a thought! Wheelman Quote Link to comment Share on other sites More sharing options...
Len Posted January 18, 2005 Share Posted January 18, 2005 Good point wheelman...that's where the fuel pressure guage taped to windshield or run thru a hole in the firewall (if you do that be sure to use high pressure fuel injection hose..even if only for temp). When you go wot look at your fuel pressure as it rises when you get max boost look to see if pressure starts to drop..if so then I would think your lines are too small (or not big enough fuel pump ...but you upgraded that) but I really don't think so. In your 240 you had carbed engine smaller lines..I believe he has an 82 zx car should have larger lines. How long since you changed your fuel filter? Quote Link to comment Share on other sites More sharing options...
TimZ Posted January 18, 2005 Share Posted January 18, 2005 Good point wheelman...that's where the fuel pressure guage taped to windshield or run thru a hole in the firewall (if you do that be sure to use high pressure fuel injection hose..even if only for temp). Yikes! Never run any kind of fuel line inside the cabin. If you want a permanent gauge, use the electrical kind. Otherwise, tape it to the windshield. Sorry Len, but us Zappa fans gotta stick together - can't have you burning yourself up... Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 18, 2005 Share Posted January 18, 2005 I have yet to see a stock L28ET making good power up to 6500rpm... Actually, with a stock head, stock cam, and stock turbo, you do very well to shift at 5000-5500 because this is ALWAYS where power starts to fall off... on every dyno chart I've ever seen of setups running these stock components. And I have looked up every one that has ever been posted here or on Zcar.com that could possibly be found And yeah with stock EFI you're going to have issues running lean at high RPM... if you tune to run rich at high rpm, you will invariably run waaaaay rich in the midrange. Regardless of if you're using 370cc injectors, or upping fuel pressure in one way or another, tweaking the AFM spring pressure, or even running bone stock setup, the stock ECU always gives the same shape a/f ratio curve, which has three pretty distinct 'steps'. Which is, it dips rich in the midrange, from when boost hits up to about 4k rpm, then leans out above 4k, then leans out much more dramatically after 5k and just keeps leaning from there. As above, I have seen this same a/f pattern on every dyno chart I've seen where the car was running the stock ECU. It makes me lust for the 300ZX ECU, which provides a wonderful, even 12:1 fuel curve all the way up even at like 14psi *drool*. I have tuned my car (via fuel pressure) to where it runs just rich enough by 6000rpm to be the ragged edge of safe at a mid 12:1, and have just settled with the very rich 10:1 mid range. I very very rarely ever go past 5500rpm anyways. Quote Link to comment Share on other sites More sharing options...
Len Posted January 18, 2005 Share Posted January 18, 2005 Tim "its better to burn out than fad away" I guess I have played the odd's a few times by installing in cab...just that wind kept on blowing it around...also eyesight getting so bad can't see pressure guage readings at wot 80+ mph and trying to drive the car safely (think that's an oxymoron) Bastaad..no arguement here concerning pitfalls of caveman stock ecu. Good analigy mentioning "steps" as compaired to a rounded fuel curve. That's why I currently have a 1988 300zx turbo parts car in my back yard. If I can find time...I want to do the "switch". My suggestions are ways I have found to get the utmost from what we have..and trying to compensate between pig rich at low end and lean at wot. Using our three parameters afm, afpr, timing. As long as everything else is in good working order ie fuel filter, ecu... Another other way to help lean at wot...a friend of mine installed two injectors just before TB with a boost activated switch turning them on when at 10 or so plus psi (used to buy from Dawes). Quote Link to comment Share on other sites More sharing options...
EZ-E Posted January 19, 2005 Author Share Posted January 19, 2005 Well that is the information I needed to know. Thanks for the heads up Bastaad. That totally explains a lot and I see it somewhat from when I drive it, when the car first starts boostin I can see how rich it runs from the huge black plume exiting my exhaust. Then as you said as the RPM's go higher it clears up straight away. Great explanation, I agree with the steps as well. Thanks! Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 19, 2005 Share Posted January 19, 2005 I'm on the computer at work right now (it's about the only time I have to post on the boards anymore, if any of you have wondered why I've been so quiet lately!) or else I'd repost a couple of my dyno sheets with the a/f curves so you could easier visualize it. I too have always had a bit of rich black smoke whenever boost comes on, even when I was running 10psi with all stock fuel system. The BEGI FPR I installed has actually preserved the fuel curve exactly as it was back then, just allowed me to move the whole fuel curve up and down. I still haven't got a chance to test out the parts that BEGI sent me, but supposedly they should allow me to almost completely tune out super rich dip when boost comes on, by causing the FPR to react more slowly and not 'come on' until a higher boost level is reached (right now it comes on full at about 3psi... way too soon). Personally, I don't think any combination of tweaking the fuel pressure and afm will really ever eliminate the rich spike or give anything like an ideal, flat fuel curve. I agree with using extra injectors triggered by boost AND rpm as the perfect way to augment the stock EFI and get a much more ideal fuel curve. Even if you just triggered it by boost, you're still most likely going to end up too rich at some point, as the stock fuel system provides a LOT of fuel by itself in the mid RPM's, even at higher boost levels like 12 and 14psi. Same sort of problem if you only triggered it by RPM, as you might be revving high w/o actually being on boost. I haven't seen a EIC that could be triggered by both, but admittedly, I haven't looked too hard Quote Link to comment Share on other sites More sharing options...
Len Posted January 19, 2005 Share Posted January 19, 2005 we are working with cave man electronics... That said I remember past phone conversations with ScottyMiz. He always told me "tighten that AFM spring as far as it will go" he mentioned he even broke one spring that way. In that way you are addressing the initial rich condition the best way you can. Which isn't that good but its all we have. bastaad said...."Personally, I don't think any combination of tweaking the fuel pressure and afm will really ever eliminate the rich spike or give anything like an ideal, flat fuel curve." I Agree we are dealing with what we have ..and making the best of it. BTY SDS also offers an x-tra pair of 460 injecter install indexed by boost. But at the price.... we could really take care of things with a standalone systum. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 19, 2005 Share Posted January 19, 2005 If I tighten the AFM spring much more than even 1/16 of a turn (like 4-5 gear teeth on the plastic wheel) the car runs very crappy, starts misfiring, choking and bogging. Loosening it much has a similiar effect, but not as dramatically per the amount of adjustment. My car even seems to like to idle pretty rich, as it idles around 12:1 happily. If I tightened it 'as far as it would go' I'm pretty sure the car would not run at all One 'sorta solution' I was kinda experimenting with, which maybe sounds mickey mouse to some, is to 'tailor' the boost curve to the fuel curve, and thus make the best use of the extra fuel the EFI throws in there. I had my car set up for a while to run a higher boost level at onset and then slowly taper off as revs increased. This did somewhat alleviate the rich midrange while also allowing the top end to stay nice and safe. It gave the added bonus of a nice fat increase in torque from 3-4k rpm. That setup came about kind of randomly as I was experimenting, and for reasons discussed in depth on another thread, finally I did decide to just switch things around to give a steady 14psi at all times. You may want to consider trying that if you have the means... I cannot stress enough the importance of tuning with a W/B O2 if you decide to go that route though. Quote Link to comment Share on other sites More sharing options...
BleachZee Posted March 29, 2005 Share Posted March 29, 2005 Regardless of if you're using 370cc injectors, or upping fuel pressure in one way or another, tweaking the AFM spring pressure, or even running bone stock setup, the stock ECU always gives the same shape a/f ratio curve, which has three pretty distinct 'steps'. This is the answer I was thinking but hoping wasn't true. So is the point of the larger flowing injectors mainly just for the midrange torque and to help a little on the upper rpms? (using the stock ECU) The rising rate fuel pressure regulator rises the fuel pressure by boost only so I guess once you're at max boost it wont' change the pressure when your rpms cause the fuel mixture to lean out... [is the adjustable FPR the same as a Rising rate FPR?] With this in mind, what is the maximum we can expect out of the stock turbo and electronics? 370cc injectors, stock T3, small quality intercooler, stock ECU ect, AFPR or rising rate....? keep it at what psi, 12-14? Quote Link to comment Share on other sites More sharing options...
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