D15Z1 Engine surging, help needed...
 

Got the d15z1 full swapped into my crx. Engine started up no problem, no cels. Engine idles great, revs fine, but has a hesitation/surging problem around ~1500rpm at part throttle (think trying to take off in first gear). Have gone through all the vacuum diagrams and everything is hooked up right. Any ideas?

Vacuum leak? Where's it idling?

idling at 600rpm, checked vacuum equals 15psi at idle, timing is set right on as well.

Can you monitor the afrs and see what they're doing around the time of the stumble?

Not really, I can monitor the voltage on the o2 sensor, but thats about it without a afr guage

Is it the lean burn? My civic does that when i drive gently and hesitates when i bring on the throttle a little. I heard its the lean burn being weak and it takes the ecu a second to come out of lean burn. I dunno. Me heads fried, the hatchets are gone to bed and i'm skulling a few cans to settle me nerves!!

ollie

^ I'm also thinking it might be lean-burn. Monitoring the volts should be enough, since you can see the change to tell whether you're in lean burn or not.

Ok, so i measured the voltage across vs+/vs- and ip+/ip-. I also tested a few more things. the engine runs fine at part throttle up until 1450rpm, then the engine starts surging at any speed at part throttle, but runs fine at full throttle. So, that being said here's what I came up with:

vs+ idle +.5v, drops to +.39v while surging
ip+ idle pretty steady at +.47-.5v with the occasional drop to 0v. at 1300rpm it picks up to +.65v with the occasional drop to 0v. while surging it goes back and forth from +1.07v to +.7v

ok, i'm lost!

Yeah, me too. I wonder if the o2 is just dead and being funky. Try unplugging it and seeing if it still does it.

I was thinking the same thing. It's a brand new 5-wire though :mad: I'm also trying to get a hold of a ca ecu to take lean burn out of the equation.

Where'd you buy the sensor?

ebay :rolleyes:

well that settles it, sensor is faulty. engine runs fine with it disconnected. Going to try and get a refund or new sensor from seller (not very optimistic), but hopefully the voltage readings will be convincing enough.

What was the name of the seller?

quality_auto_parts. Just sent them a message a bit ago, so to early to pass judgment yet.

Hmm, that's who I bought mine from and it works fine. Hope they treat you well or I'll help yell at them.

So far so good, the seller offered a refund or replacement. Sent it back this morning for a replacement so should know next week.

:thumbup:

Ok, now I'm stumped. New laf sensor, same result...:mad:

Just for reference, this is what I got:
http://cgi.ebay.com/ebaymotors/ws/eB...m=330241415768

The vacuum at idle seems too low. Usually it is about 20 inches. Maybe your timing belt has been installed incorrectly. Try taking off the belt cover and checking the timing marks for the camshaft sprocket. Be sure to reset the ignition timing if you change the valve timing.

If you can put a high input impedance voltmeter (such as a digital voltmeter) in the car and connect it to the oxygen sensor with a long wire, it may help you to find out if the fuel mixture is correct. A passenger could read it while you drive.

What is the meaning of VS+ and IP+? Are these oxygen sensor signals? I'm thinking that the signal on IP+ may indicate that the mixture is rich when you have surging.

Ok, so I finally got it this problem sorted out. After all the fuss about the laf sensor, it turned out to be an improperly install tps. The tps sensor should register .5v with the engine off and throttle closed and 4.5 at wot. Mine was 0v until part throttle, at which point the voltage would come up to the idle point and cause the engine to start surging as the ecu tried to compensate for lean/rich with the injectors.

New problem though. Engine runs really well, however i took it out for ~15mi test drive on the highway and when i go up a hill in 3rd gear the engine will start blowing blue smoke. If i lay off the engine for a second it'll go away. But's it's definitely a plume of blue smoke.

I don't know whether it's because it's a jdm motor and i just need to run some miles through it to clean it out or whether it's the valve stem seals that need replacing. I guess I could throw some seafoam in there too...open to other suggestions as well.

Weird on the TPS, I've heard of them getting out of whack but never like such (I guess it's different on the z1 though). I'd try for the seafoam and see what's up. Bummer

I'm planning on seafoaming it later today and putting some more miles on it and hopefully it goes away. In the mean time it passed ca smog this morning with flying colors. Now I'm off to register it....

This could be a problem with the PCV system. If there is too much leakage past the pistons, it could carry some oil through the PCV hose and into the air intake. You could check the compression pressure. Lower than normal pressure means something is leaking or the valve timing is wrong. A higher viscosity oil could help to reduce this problem.

yup checking compression is next up. I seafoamed it, but it's still doing it, although not as bad. I drove it 90 miles and it did it twice. Each time the engine was under load around 3200-3500 rpm ( I live in the mountains and clearing multi-thousand foot passes is a way of life). I just held the throttle position and it stopped after about 5 seconds. I can smell the oil burning before it happens too, and then POOF! I haven't ruled out an external leak onto the exhaust manifold either. BTW, I'm running synthentic oil in there, so I may switch to regular and see if it clears up too. Who knows...:confused:

Ok, figured out what was going on. Somehow (I have to be at fault here since I filled it) an extra quart of oil ended up in the engine. I drained it to the appropriate level and problem solved. I also ended up seafoaming the engine...twice...and boy does it run pertty now :D

:thumbup: Always check the simple stuff, eh?

Alright I need Vacuum Diagrams/ Oxygen Sensor Diagram
 

so i installed my D15Z1 but i didn't realize that i was missing some hoses i bought the hoses but don't know where they go? and help? i have no clue where my EGR valve connects to?

also my oxygen sensor wires were cut and i need to rewire them. can anybody help me... please.


Email me with any help at toxcma05@aol.com