Garrett76Zt Posted October 8, 2003 Share Posted October 8, 2003 Ok, first I'll state the problem, how it came about and then all the facts I can think of. -Running 10 psi boost the car pulls strong to about 3500-4000 and then stops pulling. Boost gauge stays at 10 psi, and the rpm's still go up but the car is not pulling any longer. Just kinda feels flat. If I lower boost to 8 psi or raise it to 12 psi it feels no different. - The car was running great a few nights ago, pulling strong to redline. I went out and really got on it a few times, really ran it hard. No problems. On my way home I noticed really bad gas fumes. running extremely rich. So the next day I leaned it out on the AFM so that is was back to a manageable smell. Now I notice that I have this problem. It could have been there the night before on my way home, but I really wasn't driving it hard on the way home. -So I pull the plugs and they are white, like it is running lean. so I turn boost down, richin the mixture back up and go again. Same problem, doesn't pull past 3500 or so. So I upgrade the fuel pump and still no better -Now that I have it richened, I pull the plugs and they are nice and golden, just about right, but I still have my problem. Ok . . .facts -new T-Rex fuel pump -new fuel filter -cap and rotor look fine -new NGK's -timing is at 20 BTDC -compression is a strong 135-140 across the board -new CHTS potential problems -static fuel pressure is at 40psi(using stock regulator)if this is rich at idle would it be causing my problem under boost? Wouldn't my plugs be fouled? Would a bad regulator do this? -other sensors? knock, O2, etc? Please help me out here, I'm kinda stumped! Thanks, Garrett Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted October 8, 2003 Share Posted October 8, 2003 If your RPMs are going up but the car is not accelerating the only possible cause is a slipping clutch. (or spinning tires) If you meant that the RPMs are going up but it doesnt seem to have any power (is still accelerating though) then your mixture is probably too lean. Link to comment Share on other sites More sharing options...
Garrett76Zt Posted October 8, 2003 Author Share Posted October 8, 2003 Well, this is certainly not a clutch problem. If it was running that lean wouldn't I see it on the plugs? And how is it running lean with 40 psi static fuel pressure? Any more thoughts? I gotta figure this out! Link to comment Share on other sites More sharing options...
awd92gsx Posted October 8, 2003 Share Posted October 8, 2003 It's possible you have developed a leak between your AFM and the turbo...that would cause it to run lean... Typically, if you have a boost leak, it will run rich, which would explain all of the symptoms except for the white plugs. Link to comment Share on other sites More sharing options...
240hoke Posted October 8, 2003 Share Posted October 8, 2003 What about maybe ign retard due to pinging or faulty knock sensor. i would think that would do it. maybe somthing to check out anyway. -Austin Hoke Link to comment Share on other sites More sharing options...
BLKMGK Posted October 9, 2003 Share Posted October 9, 2003 Have you considered purchasing a W/B? You're tuning blind without one and since prices have come down it's crazy to try and tune, risking an expensive motor, without one.... Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted October 9, 2003 Share Posted October 9, 2003 And how is it running lean with 40 psi static fuel pressure? I'm not an FI specialist but, as far as i know, the fuel pressure would be no indication of how the injectors are functioning. BTW, O2 sensor would be a good next step. Link to comment Share on other sites More sharing options...
awd92gsx Posted October 9, 2003 Share Posted October 9, 2003 O2 sensors don't control WOT operation. Most ECU's (even new ones) stop looking at the O2 sensor past a certain percentage of the throttle and/or rpm. Link to comment Share on other sites More sharing options...
Garrett76Zt Posted October 9, 2003 Author Share Posted October 9, 2003 Ok, well I will go ahead and do a thorough look for vacuum/boost leaks. Also about the knock sensor, can this be checked by taking a wrench and tapping the block while checking to see if the timing is retarded? Link to comment Share on other sites More sharing options...
Garrett76Zt Posted October 9, 2003 Author Share Posted October 9, 2003 Ok, I just got back from another test run. My pressure gauge reads 20 at idle when warm, so I am pretty sure I don't have a significant vacuum leak. I have tuned the afm so lean that it turns the plugs white and so rich that it turns the plugs black, but at no time did this problem go away. so i guess it has to be either a component that is causing a significant A/F change under high load or a non A/F component all together. I adjusted the TPS with no change, disconnected the TPS with no change, disconnected the knock sensor with no change. I don't know how the knock sensor works, except that it retards timing when it detects knock. Would this happen if it was bad? Or when it was even disconnected? Any more ideas?This has to be something pretty simple because it was running well within the past 3-4 days. Please keep the ideas coming, I am really stumped!!! Link to comment Share on other sites More sharing options...
awd92gsx Posted October 9, 2003 Share Posted October 9, 2003 Have you tried pressure testing your intake? Link to comment Share on other sites More sharing options...
SleeperZ Posted October 9, 2003 Share Posted October 9, 2003 Yeah, I don't think taking a vacuum reading will tell you if you have a leak. The engine is going to draw the intake down, regardless of where in the intake it is. The only place you will see a vacuum leak from a measurement is if it's after the throttle, as it's the throttle that the engine works behind to create the vacuum. Double check the all the connections between the AFM and the throttle, especially after the turbo compressor -- that's what will cause the engine to run lean off-boost and rich on-boost. Link to comment Share on other sites More sharing options...
awd92gsx Posted October 9, 2003 Share Posted October 9, 2003 If you have an air compressor and about $10, you can fashion your own intake pressurizer...these can be invaluable for finding problems like yours. Link to comment Share on other sites More sharing options...
Garrett76Zt Posted October 9, 2003 Author Share Posted October 9, 2003 Well, I'm reading pressure off my boost gauge which is plumbed into the intake manifold. Is this not good for an accurate reading? Link to comment Share on other sites More sharing options...
Forrest Posted October 9, 2003 Share Posted October 9, 2003 I don't know if this is related to your problem, but if your fuel pressure is reading 40psi, your FPR is probably stuck open. Stock fuel pressure is supposed to read 36 with the pump on, engine off, and 29 idling. (I'm surprised no one mentioned this when you said it was so high. Am I missing something guys?) When I had this problem, it made my car run too rich, which resulted in poor performance and hesitation. Edit: This is for NA. Is turbo pressure normally higher? The bosch book I have doesn't differentiate. Link to comment Share on other sites More sharing options...
SleeperZ Posted October 9, 2003 Share Posted October 9, 2003 Well, I'm reading pressure off my boost gauge which is plumbed into the intake manifold. Is this not good for an accurate reading? No, because it's on the other side of the throttle from the potential leak. The engine will pull the vacuum it needs, regardless of whether the air is metered or not. Link to comment Share on other sites More sharing options...
Guest Zcarsmakemyheadhurt Posted October 10, 2003 Share Posted October 10, 2003 How much tuneabilty are you guys getting out of these airflow meters? Because if I'm not mistaken once its open it is open. You can maybe adust the injection time a little at idle, or tune the slope of the of enrichment. But not much guys. I would look at harness connection at the ECU and AFM. Try to make the car as close to stock as possable, push the boost up a little don't have to high a expection on a small injector and 25yr old technoligy. Your thinking is right but you need a programalbe standalone to back it up. Good luck, enjoy the ride. Link to comment Share on other sites More sharing options...
SleeperZ Posted October 10, 2003 Share Posted October 10, 2003 How much tuneabilty are you guys getting out of these airflow meters? Because if I'm not mistaken once its open it is open. You can maybe adust the injection time a little at idle, or tune the slope of the of enrichment. But not much guys. I would look at harness connection at the ECU and AFM. Try to make the car as close to stock as possable, push the boost up a little don't have to high a expection on a small injector and 25yr old technoligy. Your thinking is right but you need a programalbe standalone to back it up. Good luck, enjoy the ride. Lol! With those "small" injectors I ran a 13.2 @ 104. 14 psi boost, better known as 12 psi at sea level. The factory stuff is great for moderate performance levels, and you don't have to be rich or a genius at rewiring or tuning a stand-alone. Link to comment Share on other sites More sharing options...
vashonz Posted October 10, 2003 Share Posted October 10, 2003 I recently (last 2 days) had the same problem. Was running like crap, wouldnt rev past 4000, asked local z guy about it, he said either injector problem, bad connection on ecu, or a bad dist/cas. On the way home it got to the point where it wouldn't go past ~2500, boost was very erratic. Cleaned all the connectors(CRC brakecleen), blew them out with air, now the car doesnt run at all. All Spark Plugs are white, way too clean. No spark to cylinders, spark to cap only after I go from start to run position. Replace distributor (I had an extra one, lucky me), use the same cap, same wires: runs great now, small problem starting off, but i think thats due to high fuel pressure. Tomorrow after work I'll check the plugs again(I drove it alot, hard, today) if its running better ill be sure to see. Only problems are that as soon as I started the car, the tach died. And today the fan clutch froze up(makes things loud). Yay for parts cars. Link to comment Share on other sites More sharing options...
awd92gsx Posted October 10, 2003 Share Posted October 10, 2003 I'm still trying to remember his name...but...there was somebody that used to be on this board that was running a stock 280Z ECU and was running solid 12's... Link to comment Share on other sites More sharing options...
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