Dr John

[technoman]

Dr John. I have a question about my KA24DE. On a cold start I will start the engine and it fires up drops to around 400rpm jumps back up to 1100 until it gets warm never dies except one time. After it gets warm it idles around 800. I bumped up the base idle so it got a little better but that’s what it does now on a cold start. It didn’t do this until I added 44K to a tank of gas. It has to be something to do with my I.A.C valve I am running larger cams than stock so the motor shakes a little when its warm mostly because of the cams. But its seams a little different now like there could be a vacuum leak. My check engine light stays on because I have no kat so if another code is their I would not know it.What do you think?

RegardsRob Stanley

[SpeedingMonk]

im not a tech nor am i Dr John but i do know..

"My check engine light stays on because I have no kat so if another code is their I would not know it."

u can tell. u can call Nissan Publacations @ 1-800-247-5321 an order the Nissan Repair Manual it causts 73 bean i believe or u can go get a "chiltions" for that model at it tells u in there to the chiltions is more GENRAL and BROADER when it comes to the info the Nissan manual will be for ur modle alone. u need a tool (forgot what) to read some codes, that ur car key (to turn ing. for the ecu) an a manual....

of u could always take it to the dealer i beleive it costs 50 to trough it on the computer there......... hope this helps peace

[technoman]

The code is 420. That means I have no kat. Basicly the rear 02 sensor is getting the wrong reading but o-well im not putting another kat back on the car. I never wanned to remove the Kat but my header replaced it. I do have a Nissan service manual for a 98 240 so no problem there. As far as my I.A.C.V ill just take it apart and clean it and check for leaks.

[SpeedingMonk]

u think the oraginal kat would make the same resaults?

[technoman]

u think the oraginal kat would make the same resaults?

No my 240 runs way bettter with no kat. The exhaust is set up to flow as fast as possable and is tuned perfectly. The amount of torque it makes at low rpm lets me know the it's the perfect set up. The porting helps as well.....

[SpeedingMonk]

hehehe thats funny +D but not what i meant im not a newbie man +D

"That means I have no kat. Basicly the rear 02 sensor is getting the wrong reading." - you

Originally posted by SpeedingMonk u think the oraginal kat would make the same resaults? ... i assume that the o2 sensor is getting the wroung reading cuz the sensor is covered w/ dirtty a** exhaust gas. now the oraginoal KAT on my car would be 120k miles old... also no use now. my point is ...

u think the oraginal kat would make the same resaults*?

**Basicly the rear 02 sensor is getting the wrong reading.**(because the KAT isnt filtering any exhaust couvering the sensor w/ soot... like it would do w/out a kat...)

[technoman]

I’m sure that’s why the code is on. Like you said the sensor is all dirty with soot. My muffler tip gets real black on the inside So I know its rich. I replaced the wires yesterday with excel 8 mill wires and bead blasted the plugs. I have a 95 ECU I need to get JWT to program. They can add a diode in the ECU to fool the computer. I just don't have the money yet.

[drjohn]

Technoman, It's quit possible you have a vac. leak when cold that doesn't show up when hot. It only takes a small leak when cold to cause this type of idle. Put the fact that it happened after the 44k has me curious. You could have one injector dibbling instead of spraying. The 44k comes through the injectors and into the cylinder head ports do to the placement of the injectors in the manifold so I don't see how the 44k could affect anything other than the injectors. The 44k could have dislodged a deposit in the fuel line or rubber feed hose and may have gotten into a injector.This may account for the rich mixture.

[technoman]

Do you think it could have passed the fuel filter? Nissan fuel filters work well. Should I pull the injectors and test them?

[SpeedingMonk]

i have the same prob. but i never put n e thing in the tank (recantly) how ever the hose on the top of the head is lose( the 1 comming of the air intake) is it possable the heat from the enging shrinkes the rubber hose to form a better seal? and then prevent it from happing again (while hot)

aye 1 know a good source for tech info, and diagrams on the s13? or perhaps books explaining the enginering of the engine? ty

[drjohn]

Don't forget you have a rubber fuel line between the filter and the engine , after the filter.