Guest Navy280Z Posted March 28, 2005 Share Posted March 28, 2005 Okay, a couple things to get us started. 1) I DID do a search, and couldn't find anything pertaining to this particular problem, so all of those out there who wanna say "do a search" because they're either a) too lazy to post a response, or too full of themselves to lower themselves to answer a post from a new member, you know exactly what to do with yourselves. 2) I know that this might not actually belong under "fuel delivery", but it was the closest that I could find pertaining to the subject. So I was an idiot and bought the 60mm TB from MSA. I aknowledge that I was an idiot. Once again MSA didn't send me all the parts, but it's amazing that it only takes two hours, a lot of stretching, and some vaseline to make the hose from the air flow sensor fit over the new TB, which is 10mm larger...hmmm.... Well, here's the thing... I can't get the car to idle. It'll start at about 1200, then lower to 500, then die. And then if I rev it, it'll be delayed, jump about 1500-2000 RPM, and then do the whole dying thing all over again. So just for kicks, I drove it around a bit. When she DID feel like driving, she went to about 3000 and stayed there. UNLESS I shifted into neutral, and then she just wanted to stay at about 4000 and would stay there until I turned the car off. So I'm thinking maybe linkage or actually the little spring thing on the side of the TB. I'd appreciate any thoughts. Have a good night, and Happy Easter. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted March 28, 2005 Share Posted March 28, 2005 Maybe you have the TPS hooked up wrong, or not adjusted, or maybe they gave you a pontentiometer type other then a switch type... Mario Quote Link to comment Share on other sites More sharing options...
datsunlover Posted March 28, 2005 Share Posted March 28, 2005 I would think the main reason for folks not responding to this would be simply a lack of knowlege or a proper answer to your question, nothing more.. At least thats what I've come to expect from most members here.. To the question; I'd agree with the tps thought.. I'm not sure if they changed it somewhere along the way, but my 75 280z had a TVS (throttle valve switch) that was just basicaly two positions, only one of which would be conected at a time. I'm pretty sure the ZX's went to a TPS (throttle position sensor, which is the potentiometer) but am unclear on something. perhaps a few 280z's got a tps? Anyway, when I was trying to sort out my rough running/sputering FI'd motor, I messed around with the tvs and at one point, just to see, rigged a newer TPS to it.. from a 91 escort GT I believe (same size box, "DENSO" sticker on it, fit right on.. upside down though..) and had simmilar revving issues. 600rpm, up to 3000, back down, up, ect. Barring that (say you.. swaped on your original tvs/tps to the new throttle body) maybe there is an air flow problem now that the ecu can't sort out? If the new throttle body is 10mm bigger, that would mean.. a 5mm flat surface/obstruction that incoming air has to 'hit' coming through the throttle body.. Maybe I'm way off, but thats what I'm thinking at this moment... Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted March 28, 2005 Share Posted March 28, 2005 No 280ZX ever came with a potentiometer type TPS. I think the mid/late 80's 300zx's got it though. Still, just pop-off the cover and see if it has a potentiometer or a bearing with a contact to each side of it. Mario Quote Link to comment Share on other sites More sharing options...
Guest Navy280Z Posted March 28, 2005 Share Posted March 28, 2005 Well, I got the installation of the TB correct I think. The only thing that I was missing afterwards was that little electrical cable that went into the bottom of the old TB...I have no clue what that is, but there wasn't a hole for it on the new one, so I didn't worry about it. As far as adjustments go, according to the instructions, on the throttle switch I'm supposed to rotate clockwise until I get continuity. Then I'm supposed to go back the other direction until I get an open circuit. Well that's all well and good, but I had a closed circuit the whole time. I couldn't GET an open circuit. Also, this was after I was supposed to set the idle speed to the manufacturers specification, using the by-pass screw. I couldn't get the car to properly idle in the first place...golly... Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted March 28, 2005 Share Posted March 28, 2005 Take a look at this link............ http://www.atlanticz.ca/zclub/techtips/tps/index.html LARRY Quote Link to comment Share on other sites More sharing options...
Guest Navy280Z Posted March 28, 2005 Share Posted March 28, 2005 Thanks Larry. Yeah, those were great pictures and an awesome explanation and helps me understand the big picture. My question I guess now is how do I get it to: A) Idle, and stay at 1400RPM? I set the idle by-pass screw for an idle of about 800RPM. Then it'll go four about a minute, start coughing, and then die. Also, whenever I try to bring it up to 1400 RPM, it'll surge up to about three or four thousand, and then come back down... throttle linkage problem maybe? Also, thanks to everyone for responding and helping out. Sorry I was such a dick in my first post. I won't ever post after that many beers again. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted March 28, 2005 Share Posted March 28, 2005 Is it possible that the throttle blade is rubbing on the adapter, or the linkage is hanging up on something? Try disconnecting the linkage from the throttle body and blip the throttle by hand directly at the TB. See if it is going through its motion smoothly.... Only other thing I can think of is vacuum leak somewhere..... Tim BTW...you do have the ability to edit your first post.... Quote Link to comment Share on other sites More sharing options...
fl327 Posted March 28, 2005 Share Posted March 28, 2005 Just had the same issue on a 280z. What happened on was when I installed the newer throttle body, I couldnt use the Air Regulator and had to reroute the hose from the cam cover. I tried to plumb that hose right in front of the tb, it really didnt like that and wouldnt idle. Couldnt plumb it in factory style ahead of the tb just behind the afm, so I plugged it off and ran a breather on the cam cover and now it idles. Also check the return spring. Unplug the tps and see if anything changes. if tps is at fault unplugging it will cause car to run a little richer but symtoms will go away. ALso could be a small vacum leak from the throttle body flange. You may have also ripped the boot stretching it over the tb as well, and caused a leak causing it to stall. Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted March 29, 2005 Share Posted March 29, 2005 One more thought to what's been posted. Have you sprayed water in the engine bay lately??? If you did the TPS can short out sending a signal to the ECU as if you released the gas pedal at wot and it will shut off the fuel making the car not rev over 3000 rpm. If you have check for moisture in the TPS switch..... LARRY Quote Link to comment Share on other sites More sharing options...
Guest Navy280Z Posted March 29, 2005 Share Posted March 29, 2005 It could very well be the return spring. That's the little spiral spring on the side of the TB? The old one used to up and down and went between the valve and a plate towards the bottom of the TB... Cole, in response to your question I looked at the switch on Sunday and it all seemed dry and clean. But that is definately a possibility... I owe you all beers next time you're in Annapolis/DC...I mean...er...cokes. Quote Link to comment Share on other sites More sharing options...
Guest Navy280Z Posted March 30, 2005 Share Posted March 30, 2005 Okay, here's what I'm going to do: 1) I've ordered the new switch from advanced auto and will install taht Friday afternoon. I figure for 30 bucks, replacing something that's nearly 30 years old, it can't hurt. 2) I'm going to take off the little rod/linkage that goes to the TB and clean it up a little, put it back on, and make sure it goes through the motions well. 3) If all that fails, I'll spray a little WD-40 on the side spring (return spring I think it's called) and see if it'll free it up a little (if it's indeed the part that is "sticking") 4) Should all this work, I might break down and take it to...yes...a real mechanic. Concerning vacuum hoses, here's what I did... I removed the spark advance and canister purge lines (took out the EGR a LONG time ago). moved the aux air valve elbow to the new TB. Then I put the vacuum advance onto the bottom of the new TB, and used a tee to connect that and the charcoal cannister purge line. Okay, I'll keep y'all posted. Thanks for everything. Grant Quote Link to comment Share on other sites More sharing options...
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