Rough Idle and Speed

[whitedragon551]

I finally got the SUV to where it would start by itself. Has 138K on the clock. There is a back story before this issue came up. Went to my daughters school, grabbed lunch, and went home. SUV ran fine the entire time. Got home and went inside to eat. About an hour later came out and SUV wouldnt start.

Recently replaced the:

Cap, Rotor, and spark plugs
Brand new Duralast Gold battery
Throttle Position Sensor
Cleaned the MAF, Throttle Body, and checked PCV valve

SUV starts fine, but after its warmed up will idle rough and RPM's will jump between 900 and 500 and eventually stall out. If it stalls it starts right back up.

No SES light as of now. Also can not get over 30MPH or so unless I accelerate extremely slow. As Im accelarating up to 20MPH it does fine, once I hit about 25MPH the RPM's shoot up to about 3500RPMS and it speeds up but very slow.

Had a SES light yesterday for the TPS because it was installed incorrectly. The spring loaded lever in the TPS was behind the bar on the throttle so it wasnt reading that the throttle was open. It has since been fixed and no SES light has appeared while the SUV is acting funny.

[PapaSmurf2k3]

Check your ignition timing for the rough idle thing, and also look for any vacuum leaks.

Shooting up in RPM but speeding up slowly sounds like a transmission issue. Check the fluid level and condition.

[whitedragon551]

Check your ignition timing for the rough idle thing, and also look for any vacuum leaks.

Shooting up in RPM but speeding up slowly sounds like a transmission issue. Check the fluid level and condition.

Timing belt was done by previous owner and ignition was never messed with.

Transmission is fine. Fluids are good.

Before these issues I had drove to my daughters school in it, grabbed lunch and came home. Ate lunch inside and went back to leave an hour later and it wouldnt start.

[PapaSmurf2k3]

Have you tried completely disconnecting the TPS or putting a multi-meter on it to make sure it is reading correctly?

I'd also still check for vacuum leaks. Listen for hissing, or spray some starting fluid into some suspect areas to see if it idles up (once started).
The only other thing I can think of is that it is being starved for fuel, or timing is way off (either valve of ignition).

[whitedragon551]

Have you tried completely disconnecting the TPS or putting a multi-meter on it to make sure it is reading correctly?

I'd also still check for vacuum leaks. Listen for hissing, or spray some starting fluid into some suspect areas to see if it idles up (once started).
The only other thing I can think of is that it is being starved for fuel, or timing is way off (either valve of ignition).

Replaced the TPS and installed it wrong. After I found out it was installed wrong due to the SES light I disconnected the battery to reset the light, the TPS harnesses and installed it properly. SES light isnt coming back on so I know its reading right.

Im thinking maybe a TPS relearn?

[whitedragon551]

To the top. Lets get this solved.

[yngw13]

it almost sounds like someones same problem here...but his was running crappy...he just cleared out the vacuum lines...it was clogged somewhat....good luck

[whitedragon551]

it almost sounds like someones same problem here...but his was running crappy...he just cleared out the vacuum lines...it was clogged somewhat....good luck

And how did he do that? Could you refer me to a post?

[yngw13]

new-cold-air-intake-now-running-slow-t568793.html


he had a code though...
from what I recall on other issued like this they blow compressed air to clean out the air tubes...I have never done it myself...


my advice would be to have an OBD scanner attached to your car just incase that iffy SES light went out on you...

[whitedragon551]

new-cold-air-intake-now-running-slow-t568793.html


he had a code though...
from what I recall on other issued like this they blow compressed air to clean out the air tubes...I have never done it myself...


my advice would be to have an OBD scanner attached to your car just incase that iffy SES light went out on you...

SES light didnt go out. If I turn on Acc it comes on. Just had it scanned as well before the TPS was installed properly.

Ill try a IACV relearn and the TPS relearn.

Would a dirty PCV valve cause this issue?

[Towncivilian]

Is the throttle body clean (both sides)? How about the IACV?

A dirty/clogged PCV valve can cause idle issues. I would replace it with a new OEM part and ensure the PCV hose is free of clogging and damage.

[whitedragon551]

Is the throttle body clean (both sides)? How about the IACV?

A dirty/clogged PCV valve can cause idle issues. I would replace it with a new OEM part and ensure the PCV hose is free of clogging and damage.

Cleaned the throttle body when I had the intake tubing off. IACV is also clean.

I did find a crack in the elbow of the intake tubing towards the front of the engine and the PCV is dirty. Looks like it was sucking in oil from the valve cover gasket leak and contaminated the throttle body plate (before I cleaned it) and the PCV. Ill be replacing that elbow and the PCV tomorrow along with an IACV relearn and TPS relearn.

[whitedragon551]

Anyone else have any ideas after I do the PCV valve?

[Poppy41]

Have you fixed your rough idle and speed problem? If not, I have recently been through quite a bout with my daughters 1998 QX4 that started with a P1444 error for an extended length of time. Since it didn't seem to affect engine performance, we just ignored the SES light. When the SUV began to stall and wouldn't restart until "it" rested for a few hours, I took it to an auto repair shop and the mechanic said he read a code that was for camshaft position sensor error. Since the sensor is imbedded in the distributor, the distributor was replaced. After a brief period, the QX4 started rough idle and rough acceleration. Back to the mechanic and he said it had an error code for the crankshaft position sensor and it was replaced. SUV continued to run rough and the mechanic said he had exhausted all his ideas for fixing the problem and suggested I take it to a dealer for repair. I moved the SUV to my garage so I could try and fix the thing. While pulling the hose off the PCV valve, I broke the plastic intake hose on the EVAP purge valve (just over the EGR valve) and had a bunch of little black balls rolling out on the engine and garage floor. This was causing my P1444 SES fault. I needed to replace the EVAP charcoal canister, EVAP vent valve, and EVAP purge valve. These parts are very expensive from the dealer to buy new (EVAP purge valve was $281.00), so I checked online and ordered from Amazon the EVAP canister ($150) and EVAP vent valve ($53). I bought a used EVAP purge valve on E-bay for $40. Don't forget to blow out the carbon balls in the line from the canister to the purge valve. This fixed my P1444 problem, but the idle and acceleration was still rough and I still had a SES light. Advanced Auto Parts read the code for free and it was P1336, crankshaft position sensor error. Went to another local repair shop and they replaced the crankshaft position sensor and it still ran rough. Clean the carbon deposits in the throttle body with no improvement. Took the SUV to a Nissan dealer and they found the new distributor was bad because of erratic distributor signals for 1 and 120 degrees. They replaced the distributor and that corrected the rough running problem. If I can offer any further assistance, let me know and I'll start on Chapter Two.