Thumper Posted August 13, 2005 Share Posted August 13, 2005 Ok I having the same problem as I did with the ghetto beast. In first and second gear boost lag is huge. 4k in first and like 3300 in second. In forth gear full boost is a 2700rpm's so I know its not the turbo or downpipe. My question is lag usually caused by car running too lean or too rich. It seems that the problem usually manifests it self after you install bigger injectors on the stock efi and adjust the afm. My first thought was it is because its too rich. But mikes lm-1 reads that i'm at 15:1 a/f ratio intill boost hits so that should rule out to rich? Any thoughts? Thanks Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted August 13, 2005 Share Posted August 13, 2005 I'm not familiar with what you are running, so I'll take a couple of wild stabs. Rear gear ratio too "stiff", ie: 3.90 or 4.10 - turbos like load, and if you don't have any, won't spool 'till later. Small diameter tires will act like this too. Bigger turbo - esp. turbine side, which can really slow down response. What type of turbo are you running? Quote Link to comment Share on other sites More sharing options...
Guest ON3GO Posted August 13, 2005 Share Posted August 13, 2005 car has a stock T3. has a 3.90 rear end. 225-60-15 rear tires Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted August 14, 2005 Share Posted August 14, 2005 I guess we have an answer then. 3.90 rear gear. Tires should make up a little of the difference, but not much. Remember that the stock ZXT's had 3.54 rear gears, even the 5 speed manuals - they like load. Try short-shifting from 1st to 2nd and see if boost builds quicker for you. (take it up to ~3500, then shift to second). If boost hits better (in 2nd) than winding it (in 1st then shifting to 2nd), then you know that your rear gear is the culprit, which is what it sounds like to me - at least for the way you want to drive the car. If so, you might want to consider a rear ratio change. Quote Link to comment Share on other sites More sharing options...
wigenOut-S30 Posted August 14, 2005 Share Posted August 14, 2005 the 15:1 air fuel ratio could be a major problem as well. That is way to lean for a turbo car when getting into boost. Ideal AF for a turbo car in boost is around 11:5. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 14, 2005 Share Posted August 14, 2005 The turbo doesn't get full spool in 1st and possibly second because the engine is just revving too fast, the turbo isn't getting a chance to catch up. By the time I hit full boost in 1st gear it's like BOOM time to shift. I think it probably is at about 4000rpm when it finally hits. Also, I get lower boost in 1st 2nd and even third, than the 13psi I have it set to run, which it does in 4th and 5th. 3.9's will exacerbate (sp?) this a bit. I run 3.5's and I still experience it a bit. So.. I dunno, this sounds sorta nomral to me. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted August 14, 2005 Share Posted August 14, 2005 you spelled it right bastaad525. I agree on the 15:1, although this would tend to keep exhaust temps higher (quicker spool?) Ther may be a negative factor that I am not accounting for here. This thread pretty much re-emphasises the need for the "package" approch to gearing and engine mods that has been hashed and rehashed in other threads, particularly when turbos are involved. I still maintain that a lower numerical rear gear is better for turbo cars. Quote Link to comment Share on other sites More sharing options...
Thumper Posted August 14, 2005 Author Share Posted August 14, 2005 Thanks for the input. Only thing is now the a/f ration is more like 12:1 and in the ghetto beast my rear-end was 3.545. And it only started doing this the day that I installed my bigger injectors. I guess I could have made the car faster that day also and that is when i started to out run my turbo? Ok who here who is running the stock injectors on the stock efi has this problem? If anybody does then it can't be the injectors. Or who here is running svo injectors on stock efi and does not have this problem? This way we know for sure. Thanks Quote Link to comment Share on other sites More sharing options...
HeatRaveR Posted August 15, 2005 Share Posted August 15, 2005 I have a stock '82 280ZXT and I also notice what may be similar symptoms in 1st, and part of 2nd, gears. I have not had my A/F ratio checked though. Quote Link to comment Share on other sites More sharing options...
wigenOut-S30 Posted August 15, 2005 Share Posted August 15, 2005 Thanks for the input. Only thing is now the a/f ration is more like 12:1 and in the ghetto beast my rear-end was 3.545. And it only started doing this the day that I installed my bigger injectors. I guess I could have made the car faster that day also and that is when i started to out run my turbo? Ok who here who is running the stock injectors on the stock efi has this problem? If anybody does then it can't be the injectors. Or who here is running svo injectors on stock efi and does not have this problem? This way we know for sure. Thanks I have stock turbo injectors, Stock ECU, stock turbo, I have the 77-79 tranny with a 3:70LSD. I get full boost well 10-11 psi @ 2600-2800 rpm. Quote Link to comment Share on other sites More sharing options...
Thumper Posted August 15, 2005 Author Share Posted August 15, 2005 WigenOut-s30 in what gear is this? In 3rd I get full boost by 2800-2900 and in 4th I get it 2600-2700. My problem seems to be in 1st and 2nd. Thanks Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted August 15, 2005 Share Posted August 15, 2005 I have a T5 tranny, and was using a 3.90 with it. With the T5 first gear, I HAD to short shift it, which was doubly hard - no boost, and hit the rev limit if I wasn't careful. I did this over and over at the strip -- pi$$ed me off. I finally went back to the 3.54, and found a useful 1st gear again. Still not full boost in first, but some, maybe 5 psi. Second gear was real nice though, the look on the WS6 driver's face when I pulled him from a stoplight was PRICELESS! Quote Link to comment Share on other sites More sharing options...
EZ-E Posted August 16, 2005 Share Posted August 16, 2005 I know this may sound stupid but I had a serious lag problem and I didnt and still dont know how it occured, but my timing was off. I searched for days and somehow the timing had changed, only by about 6 degrees but was enough to really kill boost. Once like you in the higher gears I would have my boost back properly. May be something you might want to check on. Cant hurt right? Quote Link to comment Share on other sites More sharing options...
Guest Z Draci Posted August 16, 2005 Share Posted August 16, 2005 I think you may have a problem called "turbo creep." I just came across this interesting write-up about it. Click here! He said that extensive porting inside the turbo and around the actuator gave him better results. I guess this problem might be a combination of a lot of different things! Quote Link to comment Share on other sites More sharing options...
wigenOut-S30 Posted August 16, 2005 Share Posted August 16, 2005 WigenOut-s30 in what gear is this? In 3rd I get full boost by 2800-2900 and in 4th I get it 2600-2700. My problem seems to be in 1st and 2nd. Thanks 1st and 2nd, 3rd is even sooner.. around 26-2700 rpms.. but usually when i am in 4th I dont drop anywhere near that low, Only if I am testing it. Quote Link to comment Share on other sites More sharing options...
Thumper Posted August 16, 2005 Author Share Posted August 16, 2005 I think you may have a problem called "turbo creep." I just came across this interesting write-up about it.Click here! He said that extensive porting inside the turbo and around the actuator gave him better results. I guess this problem might be a combination of a lot of different things! Actually turbo creep is when boost goes higher than what I set. Usually the turbo spinning too fast caused by the wastegate not being able to bypass enough of the exhaust gases. I am talking about turbo lag. I believe my problem is caused by my injectors and stock efi. I think if I upgrade to meqasquirt the problem will go away, but I am unsure what is causing the problem. My exhaust manifold and turbo is heavily ported, and my downpipe is a custom 2.5" mandrel bent pipe. So this is not the cause. So any more input on what could be causeing this? I believe that this is a problem that others are having and thought to be normal. Thanks Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted August 16, 2005 Share Posted August 16, 2005 I think he meant creeping turbo... Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted August 17, 2005 Share Posted August 17, 2005 Make sure that your WG flapper is closed all the way, a little bypass around the turbine would hurt you in the lower gears more than the higher gears where there is more time to spool the turbo. A cheap manual boost controller may help also, as the WG puck will not start to open as soon, helping to build boost pressure quicker. You can even cut and thread the stock actuator and use a coupler nut to make it shorter (if you are still using the stock turbo). This will give you more spring pressure on the WG puck. Doug Quote Link to comment Share on other sites More sharing options...
Pyro Posted August 17, 2005 Share Posted August 17, 2005 I vote for a fuel ratio issue or wastegate oppening problem. I had the same problem until I applied some positive boost pressure on the atmosphere pressure side of the wastegate. Not sure what wastegate you have. But on my external delta wastegate, by using a lighter spring then appling a reduced and regulated boost pressure on the vented side of the diaphragm, the boost would come at the same rpms in all gears. So for example, a 9 lb wastgate spring with 4 psi on the atmosphere side of the wastgate will make 13 psi of boost. The 4 psi is made from manifold pressure that is regulated down to 4 psi. You could try a first and second gear run without the boost line to the wastegate to see if this might be the problem. If the boost comes up in first gear like it does in 4th, then you need to do something to that wastgate. But, be careful not to over boost. Quote Link to comment Share on other sites More sharing options...
Thumper Posted August 17, 2005 Author Share Posted August 17, 2005 I will try to unplug the boost line and see if it comes faster. I think I had the the MBC installed backwards for the first test drive and I don't remember it spooling any quicker but its worth a try. I am running the stock t3 wastegate so I would have to thread it. I do not believe you can swap out springs on it. I'll let you know when I try it, thanks. Quote Link to comment Share on other sites More sharing options...
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