s13 / 1990 240 sx coupe manual = hesitation misfiring bucking on acceleration

[Black R]

1990 Nissan 240SX 4 cyl Two Wheel Drive Manual 220,000 miles

I did a search, but there is a lot of conflicting and confusing information out there.....

I've been having this issue for a while now:

I have an idle that will sometimes shut off the car on coastdown.

I also have a recent issue where the car overheated due to a faulty radiator. I installed the new radiator but am getting a weird lack of performance when I accelerate - it stumbles and hesitates as I press the gas pedal. It will often buck as I try to accelerate.

I also noticed when the car overheated that it blew off a hose and I'm sure water got all over the engine compartment. And when it overheated I was trying to pull off the road, but the car was acting as if I had the accelerator floored although my foot wasn't on it. I tested the throttle cable when I popped the hood and it didn't have the throttle pulled open - is it possible one of the sensors was affected and thus caused this?

After letting the car cool off and replacing the radiator and coolant, I haven't hat that problem anymore, but possibly it is related?

What should I check?

*edit* Can a moderator please move this to the nissan online mechanic section?

[silverarrow27]

Sounds like your main issue is hesitation. Check your compression and leakdown test if possible. Could be your headgasket from the overheating incident.

[jetroy240]

very common problem for high mileage s13, egr port plugged w/ carbon deposits. Just remove the screwed plugs on the intake manifold runner w/ the use of allen wrench (socket) , sometimes they are very tight, mine I have to torched it to get it to unscrew, and poked the holes there all the way down. Exhaust passes through the egr port gallery via the egr valve & is sucked through the intake manifold through these holes, then goes to the intake port straight to the combustion chambers to cool down the combustion temperatures to lower down the oxides of nitrogen (Nox)emissions for smog. If some of the holes are clogged, mostly the first 3 cylinder near egr valve, cylinder 4,3,2 are usually clogged & cylinder no. 1 is still working but partially restricted w/ carbon deposits. When egr system operates , cylinder no. 1 is not balanced w/ the other three cylinders, causing like hesitation during acceleration, feels like engine is misfiring, hydrocarbons (HC) are really high.

You probably has low idle that's why it's dying, just adjust the idle at AAC valve, follow service manual procedures.

[s13wrencher]

have you checked the fuel system (tank, pump, filter, lines,) sometimes the fuel system will be unable to supply the amount need for the right amount of air/fuel mixture there fore giving you a back fire and having lack of power when you floor it. also could be you timing usually the timing guide will break because it's made of s***y plastic. so check you timing as well good luck

[Black R]

Hi, I forgot to mention that for some reason the previous owner installed a twincam ka in this car and the wiring certainly isn't the best.

Anyway, I purchased a new fuel filter and installed it - that helped a bit, but I'm still getting the bucking or hesitation once the car is warmed up.

I also purchased a new fuel pump and will install that next.

I did read about the egr issue, and will look at that also. Thanks guys, I'll reply back if/ when I get this issue resolved.

[Cruz240Sx]

the temp sensor on the 240s is a common hesitation problem the rubber on the connector ages and breaks so it lets moisture in and corrodes the temp sensor connection causing a sputter or random shut offs or bad idle. take the connector off and check the connector and sensor for yellow or green residue on them. or it could possibly be the tps but that what i thought mine was at 1st but it ended up being the temp sensor. the fix for the temp sensor is to get a new injector 2 wire harness and splice it in or u could just clean urs. and replace the temp sensor it be the cheapest thing u have tried so far. and as for the egr blockage u can clean it like they said or get ur self some sea foam and feed it through the brake booster suction hose and it will smoke like no tomorrow but it cleans ur intake system so good u will notice a huge difference .

[cbt240sx]

I don't know if this will help or not so here goes. I have a Single Slamma and experienced the same "hesitation" issue when accelerating. Im not sure if this applies to the KA24DE, just disconnect the AIV hose running to the intake and put a cone filter on there, coming out of the black box. Like I said, not sure if this helps you but the symptons you described sounded alot like what I was experiencing last year. After disconnecting the hose, everything was fine, still ruins like a champ to this day.

[Black R]

hey thanks for the for the info. do you have a pic of where this temp sensor is at so I can check it?

the temp sensor on the 240s is a common hesitation problem the rubber on the connector ages and breaks so it lets moisture in and corrodes the temp sensor connection causing a sputter or random shut offs or bad idle. take the connector off and check the connector and sensor for yellow or green residue on them. or it could possibly be the tps but that what i thought mine was at 1st but it ended up being the temp sensor. the fix for the temp sensor is to get a new injector 2 wire harness and splice it in or u could just clean urs. and replace the temp sensor it be the cheapest thing u have tried so far. and as for the egr blockage u can clean it like they said or get ur self some sea foam and feed it through the brake booster suction hose and it will smoke like no tomorrow but it cleans ur intake system so good u will notice a huge difference .

[Black R]

ok well after replacing the fuel pump I'm still having the same issues.....

I guess it's time to look at the egr issue and the coolant temp sensor + wiring. :/

[jetroy240]

If u disable the egr by disconnecting the egr valve vacuum hose & test drive it, if hesitation goes away, it means , u have partly restricted egr gallery ports. I would clean the egr gallery ports first, or else u will end up buying parts u don't need. If u read some previous thread here, some have similar hesitation problem, but have not solve the problem for a long time. And of course, there are many causes of hesitation, could be electrical or mechanical issues. But I would check this first.