Shawn MacAnanny Posted March 29, 2009 Share Posted March 29, 2009 I just bought a 1978 Datsun 280Z which i think has the L28, and is a 5 speed which i think is the T5 transmisison. Anyway i got it for $1500, its tagged, runs and drive great... except at part throttle and where it misses and back fires badley. When it idle it sounds like my heavily cammed LS1 and i know it shouldnt haha. The engine has just had a new head put on it, or head work i forgot which. The head says N47 on it. Has new plugs, new wires. It has a cold air intake, and it also has a long tube header with 2 1/2" exhaust. Now i noticed that the EGR is blocked off. There is a provision for the EGR in the long tube but it is plugged off at well. I am thinking this may be the reason for the hesitaion or part of the reason. I am also thinking that perhaps the vane air meter could be messing up or the TPS. I know nothing about these engines i am just trying to figure out where to start. Under WOT the engine runs great!. This to me leads me to believe that it could be the EGR or the VAF as in my mind these are part throttle systems. I am going to run some injcector cleaner through it for the hell of it tomorrow while im driving it around. What do you all think? Here are some pictures. I got it to swap an LS1/T56 into but id like to drive it around in the meantime while i collect parts. http://viewmorepics.myspace.com/index.cfm?fuseaction=user.viewPicture&friendID=5884057&albumId=2523663 Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 30, 2009 Share Posted March 30, 2009 Hey man, I think you should start with checking your timing. If you think someone was just in there doing somthing to it and it sounds funny, it wouldent be a bad start. I would also check the vacuum advance on the distributor, may be somthing going on there. . When i had the stock intake it had the EGR valve on the back, which i capped off when i installed the header and never caused an issue. Just my .02, oh and mine is a 77 L28 and had an N47 on it. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted March 30, 2009 Author Share Posted March 30, 2009 What should timing be set at? I have a timing gun ill throw on there tonight and unhook the vacuum advance and see what it its at. Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 30, 2009 Share Posted March 30, 2009 I think 10 deg, but check your cam timing as well. Check other posts on timing for all specs, its not hard but has to be done right. If you have a book, check it out. Your timing may be ok at idle, but drooping through the advance, might want to hook a vacuum pump (hand operated) with a guage to your distributor advance and check for leaking...not while the car is running. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted March 30, 2009 Author Share Posted March 30, 2009 Cam timing is adjustable? Yeah im ned to OHC motors, i work on LS1s which is the plan to put on in this one. Quote Link to comment Share on other sites More sharing options...
Daeron Posted April 1, 2009 Share Posted April 1, 2009 I would bet that all of your problems are EFI related. this thread hereshould connect you to the EFI Bible, which is an invaluable resource. Chances are likely that your problem lies either in the TPS, the CTS, or possibly the thermotime sensor or cold start injector circuits, but it could be anything. The EFI bible CAN be used as a tool to verify, step by step, component by component, that the entire EFI/ignition system IS functioning 100% and then the problem MUST lie elsewhere. The cam timing remark meant basically, ensure that the timing chain is not advanced or retarded a tooth; the timing isn't adjustable per se but obviously if the chain is off.... Welcome to the Wonderful World of Inline Six Bliss!!! The stock EFI is kinda crummy for power, but using an inexpensive DIY EMS system like megasquirt can set you up for an easy 220+ horses NA (NA horsepower starts costing money quickly after this point.. but the car is light, so don't underestimate what fun 22 horse is capable of!) and then there is always the option of turbocharging. The stock turbo motor internals seem to be good for up to 400 horse, and for that you typically need a good big intercooler, some sort of intake manifold solution, (ITBs or aftermarket mani, stock EFI manis are largely restrictive TBH) injectors, and a turbo upgrade... but the longblock is still stock. And, of course, theres always the option to drop the stock motor and replace it with something more.... to your tastes. MY tastes happen to center around the Nissan L-series, so I'm no source of info for "all that hybrid junk" but Welcome to HybridZ!!! Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 1, 2009 Author Share Posted April 1, 2009 Oh intentions were to drop in a 550hp ish LS1. I am all about the ls1. Im making close to 550hp on stock, unported fbody cylinder heads, not even z06 heads. They make rediculous Hp and i get about 20mpg with my carbed ls1 and a 6 speed with 4.56s. I will read up on the efi bible though. thank you very much i was thinking it as sensor related. I did however start playing with the timing and someone cut a bunch of timing marks in the crank pulley so i have nothing to go off of. I did get another balancer with the car so i am going to install that. Also you know where the distrubutor bolts into the slot with the 10mm bolt in that adjustment slot? yeah whoever put it in decided that was too advanced so its now out of the slot with a washer and the distributor turns just counter clockwise of its origional location outside of the tab with a new hole drilled. I think that the wires may be off by one of the cap. I am not sure i havent worked on the engine more than ten minuts to see what the deal is. Quote Link to comment Share on other sites More sharing options...
thrustnut Posted April 1, 2009 Share Posted April 1, 2009 Like I said, check the obvious stuff first. You dont need to change the balancer, just rotate the crank to #1 TDC and see which notch lines up with the 0 on your timing plate. I bought an aftermarket single grove euro dampener and it has 5 notches, just figure out which ones for you and mark it. I bet your timing is crap. Checking the FI system would be good, but AFTER you make sure the engine is even capable of running right. This is all stuff that is applicable to ANY engine regardless of cylinders, displacement or horsepower. I work on 550CI twin turbo opposed air cooled six cylinders (aircraft) and it is a basic setup for them. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 2, 2009 Author Share Posted April 2, 2009 How do i line up #1 TDC without the mark on the balancer? Quote Link to comment Share on other sites More sharing options...
Filmjay Posted April 2, 2009 Share Posted April 2, 2009 As much advice as everyone has posted, I can't believe nobody has told you to check the simplest thing first....the plug wires. Quote Link to comment Share on other sites More sharing options...
Mayolives Posted April 2, 2009 Share Posted April 2, 2009 quote: How do i line up #1 TDC without the mark on the balancer? Remove the spark plugs, vallve cover and then check the adjustment on the valves. Turn the engine over by using the bolt on the crank damper until number one cylinder (the one in front) is on the top and on compression stroke. You can use your thumb to feel the compression coming up and then use a tool to feel the piston reach the top of the stroke. The two front lobes on the cam should look like the picture below and you should then be on top dead center and on the damper timing mark. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 2, 2009 Author Share Posted April 2, 2009 Anyone know what the plug gap is supposed to be? plugs are BLACK and i fiddled with the timing. The distrubutor is 180* out so when the head was replace the cam got put back in 180 out. I fixed one plug wire that the tip cmae off of and used dielexctric grease on all of them. Also had ot use an 18" breaker bar to get them loose (and im not a little guy), i shattered one plug but the rest came out ok. This is why we always use never seize. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 2, 2009 Author Share Posted April 2, 2009 Well i put new plugs in it, put the distrubutor back the way it orgionally was and its missing horribly It sounds like it running on 4 cylinders and barely revs up. It's also backfiring through the exhaust. I am going by the firing order 1-5-3-6-2-4 and mine is not from 9 oclock its from 3 o clock but still the firing order should be the same right? Also replaced the fuel filter. From replacing the fuel filter and spark plugs (gapped to .040) i saw no change. All i have done from the time it was idling poorly to running on 4 cylinder sound was take out the distrubutor, try a couple different wire combinations (since the distrubutor wasnt fastened in the correct spot) and that it. I've tried turning the distrubutor both ways to see if it helps with the sputtering or anything it doesnt. It sems like it is just running on 4 cylinders or something. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 2, 2009 Author Share Posted April 2, 2009 Also i hooked a timing light to each spark plug wire and it blinked so they are getting some sort of power. I pulled a few wires from the distrubutor side and could see them arcing but it didnt change idle quality that much. What could be causing this horrible missing? Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 2, 2009 Author Share Posted April 2, 2009 Ok let me give you all a little advice when putting your plugs in the firing order. Even though you may check that your firing order is in the correct clockwise pattern 3 times, and all the wires are in the correct order, on that 4th time you might realize that the firing order is COUNTER clock wise. I started pulling wires from the distrubutor when it was running and #6 almost shut the engine off so then i realized i had the pattern reversed hahaha i know im an idiot. Have no idea how i ower looked it i even double checked it. oh well The engine is back to the stock timing it was at. Im going to isntall the new ballancer next since i already have it and it has one tick mark and also the AC belt provision even though im sure the ac compressor is locked up on this car. I drove it for about 3 minutes up and down my driveway and it has ALOT more power but still idle poorly and runs poorly below 2000rpm. I did add some "Guranteed to PAss Emmissions" injector cleaner to it which ive found to be the best injector cleaner (i had a set of 183,000 miles turbo injectors flowed from my 3000gt one time after i used it) and the car seem to be acting slightly better but it could just have been from it warming up and being run with the new plugs and fuel filter. I need to go get the car tagged and drive it around so i can minitor different things i try legally. Once i get the other balancer on hopefully ill be able ot see what the timing is at right now. The 5 or 6 tick marks on the one i have are a pain to read and i think its just going to be easier for my to remove the balancer than the valve cover since its keyed and doesny look like i need a puller for it. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 3, 2009 Author Share Posted April 3, 2009 Ok got the new balancer on, had the tiniest bit of surface rust on it so i sanded the inside lightly and added a tiny bit of grease. I tapped it in on little with the hammer and got about 2 threads of the bolt in and pulled it it on the rest of the way. The old pullyer was harder to remove than i thought. I just used a ball joint separater against the timing cover which i know is risky but it all turned out fine. Timing was 20 degrees without vaccum advance with the 'homemade' notch the previous mechanic put in it. I put it in the factory slot and it would only advance to about 2 degrees. I made my own tab and got it down to 10 degrees. Now when i hook the vacuum advance up i get NO advance at all. How come? Timing is not affect at all by hooking up the vacuum advance. I dont have a fancy timing light but around 3500rpm the timing maxes out and i would guess it somewhere between 35-40 degrees timing. I'm going to look at the vac lines tomorrow and i have an autometer vac gauge i am going to hook up and see what kind of vacuum in getting and at what lines. It looked like the vac line the vac advance was hooked into T'd into a vac line going to the TB which then ran to a vacuum canister of some sort. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 21, 2009 Author Share Posted April 21, 2009 Ok well i found the problem. The car had the wrong AFM. i tested the one that was on there, tested perfect i bought one of Ebay with a different serial number just to try it and MAN!!! this thing runs great. Im definately holding off on putting in my 6.0L LS1 for a while this is such a fun car to drive. Quote Link to comment Share on other sites More sharing options...
Gilli Posted April 25, 2009 Share Posted April 25, 2009 Serial of the AFM that was on the car? Serial of the AFM you just bought? Thanks Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 26, 2009 Author Share Posted April 26, 2009 The one that was origionally on the car that i tested and tests fine is #A31-604-000 The one i bought that works fine is # A31-625-000 Quote Link to comment Share on other sites More sharing options...
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