KA24DE bogging, ECUTalk info?

[andkorn]

I have a bone stock '93 240sx. The car has a weird lag issue that mostly manifests itself when you stomp on the gas. The car has no power under full throttle but under light throttle it drives OK.

I am running ECUTalk and was wondering how "Timing (degrees BTDC)" is suppose to act. Under light throttle and light accel the Timing BTDC moves smoothly and mostly rises (between 20 and 40). When I stomp the gas and get the lag to act up, Timing BTDC drops to ZERO and sometimes displays a NEGATIVE number! Is this normal? Is my crank position sensor shot?

Thanks in advance.

[liquid_cool]

i have that same issue from time to time with my 240 when i romp on it...i dont have a tuned ecu thou for the mods i have...it might be a general flaw with the motor desighn ..(there are so many)..it can allso be due to the partially balanced crank not wanting to spin..maybe another nicco head can enlighten us on this issue more.

[andkorn]

I just replaced the distributor cap and rotor, the old rotor had a good 5 degrees of play in it (cheap-a** autozone parts that I didn't buy). This helped a little bit, but the car still bogs.

I also rode with my friend who has the same exact car and I logged data on my laptop (with a consult cable and ECUTalk), but I can't really make sense of the numbers. The first thing I noticed is his TPS is at 2.8V at idle while mine is 0.5V. Also his MAF is 1.32V at idle while mine is 1.22V at idle. The spreadsheet for this data is huge, but here are a few interesting items:

-----My car (bogs down).--data at idle:1162 RPM21 Degrees Timing BTDC0.5V TPS1.22V MAF0.34V O2 sensor40 Water temp103 A/F base--data at max airflow:3650 RPM29 Degrees Timing BTDC2.82v TPS3.4v MAF0.29v o2 sensor51 water temp100 a/f base

------Friend's car (runs fine).--Data at idle:1162 RPM25 Degrees Timing BTDC2.82V TPS1.32V MAF0.51V O2 sensor68 Water temp114 A/F base--data at max airflow:5462 RPM17 Degrees Timing BTDC4.14V TPS3.99V MAF0.02 o271 water temp100 A/F base

all the sensors look fine to me from this output.

I'm beginning to suspect a vacuum leak again.

[Razi]

My car has a hesitation problem as well, a bit of misfiring.It has problems while idling and driving.

Here is my data from ECUtalk.

At Idle:938 RPM21 Degrees Timing BTDC0.5V TPS1.18V MAF0.33V O2 sensor133 Water temp103 A/F base

I'm thinking I have a vacuum problem as well.I redid my vacuum hoses in the back of the intake manifold after I removed the EGR valve and such, I went off of pictures I took but some parts were missing so I had to do a bit of guess work.

If anyone has detailed pictures of the vacuum hoses in the back in the engine, I would sooo greatly appreciate it.

[andkorn]

I think my ignition timing going to zero on the gauge on the laptop was a fluke -- no where in the logs did the timing go way off.

I (mostly) found the solution to my problem.

The problem:The car runs fine at partial throttle but bogs really bad when you punch it. it seems that when the car switches from closed to open loop all hell breaks loose and the car runs like crap. There's a certain sweet spot where you get decent acceleration but if you give it a bit more gas it bogs. Also when I changed the spark plugs they were whitish - this means the car is running lean.

My friend told me that 240sx's have fuel line clogging problems. I don't know where he got this info from, but I decided to act on it.I replaced my fuel filter with a NAPA one. After about 3 days my car was much more responsive and the bog is almost completely gone.

If you read the FSM for this car it says to check the fuel pressure. If you have the tools I would say try it.

Replacing your fuel filter (see here zerothread/160213 ). make sure to do the engine cranking part. this is to remove pressure from the fuel lines. You don't want a big mess spraying everywhere. The fuel filter holds about half a cup of fuel - be ready for this. Also note that because of this the car will be difficult to start the first time. After the new fuel filter fills up and pressure is back to normal the car will be fine.

[andkorn]

sorry to wake an old thread, but this was a bad fuel pump. A trip to Napa and 45 minutes later the new fuel pump was in. The car immediately woke up and the issue was gone.

[NewKleer]

did you check O2 sensor also? 0.3v if it stays there, means its dead = bad fuel economy.

and the low temp (40) does that just mean the car wasnt warmed up? would explain timing going to 0 until car is warmed up.

[Rev_D21]

He says replacing the fuel pump fixed the problem.

[NewKleer]

i did not question that. just noticed other things which could be wrong.