1995 j30 hesitation problems

Post by **yodawill2000** » Wed Sep 17, 2008 10:07 am

I doubt its disconnected at the KS.Its not accessible without MAJOR work.Surely he wouldn't cut the wires.

Hard to believe a senior tech would even disconnect it !!!

Post by **GerryO** » Wed Sep 17, 2008 12:25 pm

yodawill2000 wrote:In Drive.The Idle seems fine but as long as Ive had the J it seems to want to downshift too early under acceleration. As in speeding up for a pass and it shifts down 2 gears instead of one.It will go down to third, then zoom down to second.poor guy I'm passing thinks I'm showing off or something.

Modified by yodawill2000 at 1:05 PM 9/17/2008

It sounds like you are enjoying the high rpm down shifts and at the risk of totally screwing things up you might try at least checking your TPS output voltage using a voltmeter, as the correct setting can: 1) lower the idle speed 2) affect/improve the shift points and OD lock-up/engine crusing rpm 3) improve gas mileage

If a '94 is like a '93, just remember to momentarily disconnect and reconnect the one connector that you'll need to insert a wire into the back of to measure the output voltage (the engine will stumble and I think doing so clears/updates a previously stored reference value in the ECM), if you decide to make any adjustments.

Post by **yodawill2000** » Wed Sep 17, 2008 1:14 pm

I glanced through the adjustment procedure in the FSM.Wasn't clear if the engine is supposed to be running or off.I'm guessing off as the sensor is just a potentiometer .I'll give it a check this weekend as the consult board I bought from Drape should be here any day.

Post by **GerryO** » Wed Sep 17, 2008 2:07 pm

yodawill2000 wrote:I glanced through the adjustment procedure in the FSM.Wasn't clear if the engine is supposed to be running or off.I'm guessing off as the sensor is just a potentiometer .I'll give it a check this weekend as the consult board I bought from Drape should be here any day.

With the engine warmed up and running/idling with the throttle closed. Cool. Let me know how the consult board works out.

Yeah, I once tried using the TPS resistance readings that are listed in the manual to set things up. That was a mistake. You have to measure/set it's output voltage to the ECM, with the engine running.

Post by **yodawill2000** » Wed Sep 17, 2008 2:11 pm

Will do.The main stats screen shows the TPS voltage.Should be easier than a multimeter for sure.looking for .4 to .5 at Idle correct ?

Post by **GerryO** » Wed Sep 17, 2008 2:17 pm

yodawill2000 wrote:Will do.The main stats screen shows the TPS voltage.Should be easier than a multimeter for sure.looking for .4 to .5 at Idle correct ?

I've read that between 0.40 and 0.45 is best. Higher voltage does seem to cause higher idle speeds and delayed/harsher shifts, but too low is bad in terms of easy down-shifts, higher rpms and hunting at crusing speeds. I recall mine as being approximately 0.438 VDC.

Post by **yodawill2000** » Wed Sep 17, 2008 2:27 pm

Betcha a donut I'm a tad low then.I'll shoot for .425Thanks GerryO !!!

Post by **GerryO** » Wed Sep 17, 2008 2:46 pm

Hmm...there's the rpms at idle in Drive when stopped factor too. I'll buy you a donut just as long as the story has a happy ending. Just a heavy right shoe maybe? How's the timing look after your belt change? If it ain't broke...

Post by **yodawill2000** » Wed Sep 17, 2008 2:55 pm

Haven't checked actually. (Timing)But trust me no heavy foot here !!Gas prices took care of that ..

Post by **mej30guy** » Thu Sep 18, 2008 3:43 am

I checked the RPMs with a warm engine, and got a 660 reading with my foot on the brake. (1 line below 1000) So I guess that's ok.

I checked out the knock sensor connection at the top of the engine and found a couple of things. First, what looks like the proper end has a yellow wire coming out of it like in the picture. Also, those wires go into a heavily taped black sheath, across the top of the engne, and into the firewall on the passenger side, hopefully to the ECU. Secondly, the other end looks like it goes down into the middle of the engine, directly to the ks. Is my assessment correct?

I received a call from a friend of mine last night who again spoke with a couple of mechanics. When he described my J's symptoms, they immediately ruled out a bad ks, and said it was most likely low fuel pressure. Their reasoning, "How would the ECU know to retard the timing if it wasn't getting a signal from the sensor?" My thought is, because it doesn't get a signal that everything is ok, the engine defaults into a retarded timing as a fail safe to guard against major league engine damage.

The possible fuel pressure issue flies in the face of the fact that I can cruise at 85mph and 2700k without a burp from the engine.

On the bright side, I found an OEM Infiniti ks for $49.95 with free shipping and a 5 year warrantee on e-bay.

Oh the humanity!!!!

Post by **yodawill2000** » Thu Sep 18, 2008 6:20 am

Your thought is correct.

Put a resistor in there to be sure.

Post by **mej30guy** » Thu Sep 18, 2008 6:29 am

I'm glad I'm on the right track. I'll try the resistor before I do anything else. I'm assuming I can pick one up at my local Shack. Once connected, will the engine respond the way it should if the ks was the problem? Or will I have to wait for an ECU readout to see if the 34 code shows up?

Can I have the size, and how-to site again?

Many thanks.

Post by **GerryO** » Thu Sep 18, 2008 7:51 am

mej30guy wrote:I'm glad I'm on the right track. I'll try the resistor before I do anything else. I'm assuming I can pick one up at my local Shack. Once connected, will the engine respond the way it should if the ks was the problem? Or will I have to wait for an ECU readout to see if the 34 code shows up?

Can I have the size, and how-to site again?

Many thanks.

As I recall a bad KS triggers a Code 34, but doesn't cause the CEL to turn ON. Do you have a Code 34 now? Try turning a Code 34 ON and OFF by disconnecting and reconnecting the KS? Isn't there a spec for resistance across its' two wires/terminals, as well as a procedure for checking the harness wires that run to the ECM?

Post by **yodawill2000** » Thu Sep 18, 2008 7:54 am

If I recall a 1.5 megaohm resistor plugged into the connector on the cable that goes back through the firewall.2 minute job.

Post by **mej30guy** » Thu Sep 18, 2008 8:48 am

I must be getting a 34 code because the ks was disconnected, but not at the top of the engine. (still connected there) Otherwise, disconnecting and reconnecting might reset the ECU.

Post by **mej30guy** » Thu Sep 18, 2008 8:59 am

My other thought was, since my ks was disconnected because it was bad, replacing it wouldn't hurt. The car runs like doo on the low end without it, so even if it may not be the major cause of the problem, a new relocated ks certainly would improve things somewhat. It's a no-lose.

That's where I'm leaning at this point.

Post by **yodawill2000** » Thu Sep 18, 2008 9:31 am

Good Mindset.That KS has been on that hot motor block for 13 years.I'll be doing the same thing soon. Mine runs great when its not fully warmed up, But I notice a little bog down when its up to temp.I'm guessing it has developed cracks that open up under heat.

Post by **mej30guy** » Thu Sep 18, 2008 10:18 am

That's exactly what my wife's J does.

I feel so much better about what I'm doing, thanks to the reinforcement I've received from this board. Nothing like it.

Once the parts arrive, and the fun starts, I'll be back for more direction.

Hopefully, the connector with the yellow wire coming out of it, was the correct connection to plug in the new ks.

Post by **yodawill2000** » Thu Sep 18, 2008 10:57 am

I'll check mine when I get off work.Don't recall the wire colors.

Post by **yodawill2000** » Thu Sep 18, 2008 1:20 pm

Hmm. Mine seems to have a black and white wire coming out of it but they are bound together with yellow tape.

If you look at the drivers side rear of the engine, you will see two connectors right in front of the brass colored crossover tube. just behind that tube and about an inch to the drivers side is where my KS connector is. Its mounted horizontally.

Anybody know if the 95 KS Harness connector is in the same place ??

Post by **mej30guy** » Fri Sep 19, 2008 2:32 am

Mine is in the same spot, tucked in behind 2 crossover tubes. However, I'd like to know on which side of the connector will I plug in the new ks. If you're looking at the engine from the front, is it the connector on the left hand side, or the one closest to the driver's side fender? (the one with the yellow wire coming our of it) That one is the one that appears to go up into the sheath that carries it across the engine and into the firewall on the passenger side.

I would seem fairly obvious because the business end of the ks wiring harness would only fit into the correct connection.

Post by **yodawill2000** » Fri Sep 19, 2008 3:03 am

If you take that connector off the metal tab that its mounted too you can tell which side goes down under the plenum to the Knock sensor.

1995 j30 hesitation problems

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