Well it goes like this, my friend had a DOHC in his car, got good fuel milage, didn't burn oil, only problems were that it wouldn't startup without giving it gas, it also had slight hesitation problems and high idle. He put in a walbro fuel pump, still wouldn't start without gas, but the hesitation seemed to go away.<fast forward>
He's doing an sr20 swap, I get the engine. Same problems, except I'm getting major hesitation. Pull the plugs, they're white, so I get a walbro. Put it in. It's now present day. The car starts fine, It might take 5-6 cranks in the morning though. It idles at 900 when its first started then heads up to 1200 and moves back and forth from 1200 to 1300. I still get alot of hesitation when the engine is cold, like I'll put it in 2nd and I give it the usual amount of gas but it's like I'm giving it alot less. Once the engine warms up I usually hit two dead spots around 2500 and 2800 rpm.
So when it comes down to it it could be something like a bad spark plug, clogged injectors, or bad o2 sensor, but that wouldn't really explain the high idle, that would be along the lines of throttle position sensor (tps) or auxilary air control (aac) valve.
Whats been done:new walbro fuel pumpnew 300zx fuel filternew coolent temp sensor
also note there is a very slight chance the spark plug wires might not be making good contact, but I've checked 'em out and I don't think this is causing any problems.
I've tryed to explain everything accuratly, things in () are keywords for searches.
Thanks in advance to anyone who can help!
high idle, hesitation when cold, dead spots when hot
Have you thought about the injectors? I'm no real car mechanic, but it sounds to me like you're having problems from an irregular fuel delivery... which makes me think injectors. Could be your fuel pressure as well though.
I donno, before you start throwing money at the problem I'd run over all your vac lines, make sure you're not getting any leaks or anything like that-- check your EGR valve to make sure it moves freely, and triple check your damn air filter haha.
Are you throwing any codes?
I donno, before you start throwing money at the problem I'd run over all your vac lines, make sure you're not getting any leaks or anything like that-- check your EGR valve to make sure it moves freely, and triple check your damn air filter haha.
Are you throwing any codes?
Re: high idle, hesitation when cold, dead spots when hot (gogg)
Update time:Seafoamed the fuel system, still have the dead spots. I'm thinking the seafoam would have unclogged the injectors or lines if they were clogged.
Also checked for intake manifold leaks, pretty sure I don't have one. But when I was doing that I noticed that at cold start it takes about 4 cranks for the car to start if I don't let the walbro pump have enough time to "prime" the car (just stick in the key and crank) and the car idles at 1500 then I go WOT and it goes down to 1300.
And finally a better explaination of the dead spots, they are more noticable when the engine is cold. When I shift into 2nd or 3rd (more noticable in 2nd) and re-apply the accelarator it's like the throttle takes about half a second to react (not as bad sometimes). I also notice when the car would be around 2500-3000 upon shifting the same issue happens (when warm, just not as bad, but noticable). So all in all there's "dead spots" around 2500-3000 rpm. I'm thinking this could be an issue with the TPS. Thanks.
Also checked for intake manifold leaks, pretty sure I don't have one. But when I was doing that I noticed that at cold start it takes about 4 cranks for the car to start if I don't let the walbro pump have enough time to "prime" the car (just stick in the key and crank) and the car idles at 1500 then I go WOT and it goes down to 1300.
And finally a better explaination of the dead spots, they are more noticable when the engine is cold. When I shift into 2nd or 3rd (more noticable in 2nd) and re-apply the accelarator it's like the throttle takes about half a second to react (not as bad sometimes). I also notice when the car would be around 2500-3000 upon shifting the same issue happens (when warm, just not as bad, but noticable). So all in all there's "dead spots" around 2500-3000 rpm. I'm thinking this could be an issue with the TPS. Thanks.
Another update: I checked the EGR, it works, but the rubber elbow vacuum hose was busted, so I replaced ... I still have all the same problems.
I'm also getting code 14 on the ecu diagnostic test, which is vehicle speed sensor.
Drove it again when it sat overnight, the hesitation is pretty bad at anything below 3000 rpm till it gets warmer, then it just has the dead spots.
Sometimes the odometer doesn't work, just like with the old engine, is this tied in with the vehicle speed sensor (vss)?
Modified by gogg at 9:22 PM 9/26/2004
I'm also getting code 14 on the ecu diagnostic test, which is vehicle speed sensor.
Drove it again when it sat overnight, the hesitation is pretty bad at anything below 3000 rpm till it gets warmer, then it just has the dead spots.
Sometimes the odometer doesn't work, just like with the old engine, is this tied in with the vehicle speed sensor (vss)?
Modified by gogg at 9:22 PM 9/26/2004
Have you replaced plugs, cap/rotor recently (wires are ok still)?
IACV valve may be a little nasty inside to. Try gettgin some carb/intake cleaner and pulling off the hose from the intake and blasting the **** out of it without letting it die.
Check your fuel pressure at idle (I think with vacuum disconnected it shoudl be 43psi, dont quote me)
Lastly check to make sure that your coolant temp sensor hasn't corroded.
IACV valve may be a little nasty inside to. Try gettgin some carb/intake cleaner and pulling off the hose from the intake and blasting the **** out of it without letting it die.
Check your fuel pressure at idle (I think with vacuum disconnected it shoudl be 43psi, dont quote me)
Lastly check to make sure that your coolant temp sensor hasn't corroded.
Re: (candela)
Update: Seafoamed intake, replaced spark plugs, and o2 sensor, cleaned up the wires.
still nothing
(could this be a result of the ditributer, rotor, or cap?)
I did a test on my IAVC-AAC and it said it wasn't working entirely correct.
The test was pinching the hose when the car was warm, the rpms went down about 100, showing the valve is open when it shouldn't be right?
Sprayed seafoam into the hose, hoping that won't mess anything up and maybe it'll fix it, although it hasnt done anything so far.
still nothing
(could this be a result of the ditributer, rotor, or cap?)
I did a test on my IAVC-AAC and it said it wasn't working entirely correct.
The test was pinching the hose when the car was warm, the rpms went down about 100, showing the valve is open when it shouldn't be right?
Sprayed seafoam into the hose, hoping that won't mess anything up and maybe it'll fix it, although it hasnt done anything so far.