Troubleshooting and terminology: help!

[Cliffy15]

Hi guys!

I've been lurking around the boards for a few months (especially the faqs) trying to find some solutions to my car problems. I am not a car guy at all (computer programming nerd) so I am lacking in much of the basics but I'm trying to learn in a last ditch effort to avoid taking my car in for Nissan servicing.

I have a FSM, but much of it is a little too technical for me as I don't know where most of the intricate little parts (like sensors) are, nor what they look like. So I'm turning, here, for help.

Here's the car: 1990 Nissan 240SX (KA24E). Bone stock. 132K Miles.

Here are the problems: A few months ago, my car began having problems starting/idling. Part of the reason was leaky injectors which was making lose fuel pressure. I've since had the seals replaced and the fuel filter changed, but occassionally (I've noticed no other trend) I have problems starting the car cold.

The car cranks fine but sometimes takes awhile to "catch". The battery is good. The starter is new. The fuel pump is good. The plugs, wires, and distributor is new. New air filter.

When I do get the car started (have to basically start with the accelerator to the floor), I have to hold the throttle open, slightly, to make sure the RPMs don't drop and stall the car. Once I get to normal operating temp, things are quite a bit better although if I let go of the throttle, the RPMs drop rapidly and alarmingly low.

This leads me to the conclusion that my car is having problems at low throttle positions.

Additionally, when I open the throttle quickly, from idle, the engine drops RPMs, almost causing a stall, then catches up.

My solutions:Clean the Mass Airflow Sensor. (Did that, no problem)

Look for intake leaks. (Did that, one found and patched).

Reground the motor. (Looking into that, but my current ground is still good)

Replace TPS (kind of expensive, was hoping to have a better diagnosis before actually buying it)

Replace O2 Sensor (still waiting for a better diagnosis)

AIV removal (finally came into the forums and looked at that, today, will attempt within the next couple of days). Still, though, I did not have the indicative oily residue on my air filter.

My questions: I've been looking through the FAQ and haven't been able to try some of the solutions because either I don't know what part is being referred to, I don't know the location of the part, or I don't know what it looks like.

I have no idea what the following does, looks like, or where they are located. If someone could provide pictures and info, I'd really appreciate it:

BPR ValveEGR ValveAAV/AAC Valve (are these the same part?)AIV/IAV (are these the same part?)

Any help would be grealy appreciated! =)

Mahalo!

[NISTECH]

check your coolant temp sensor for corrosion in the electrical connector. red or yellow 2 wire connector near the front of the intake manifold at or near the rad hose inlet. if it is corroded get some battery terminal cleaner spray it in the connector let it sit for a bit then use a pocket screw driver to scrape away the corrosion in the sensor and use a small pionted pick to slightly bend the pins in the connector a little tighter to make better contact with the pins in the sensor. then try to start your car cold.

egr is the gold sauser located at the rear of your intake manifoldi believe you mean bpt not bpr that is located right next to the egr valve and locks similer to the egr valve except it has 2 ports on top of it instead of 1.

aav/aac is located under the intake manifold near the rear.

aiv/iav is located on the drivers side of the engine compartment.info on this is in a sticky at the begining of this forum.

[topless@vabeach]

What about the fuel filter, when was the last time you changed that?

[Cliffy15]

Thanks for the replies!

NISTECH - That's the first mention of the coolant sensor that I've seen. I'll try and check it!

Can you, or someone else, explain why the coolant sensor would be giving me the problems I have been having?

TOPLESS - Yep, changed the fuel filter out two weeks ago - the same time I had the seals on my injectors changed.

[NISTECH]

because if the coolant sensor tells the ecm it is colder then it really is the ecm thinks the ficd(fast idle control device)is allowing extra air in the engine so it adds more fuel. which will cause the vehicle to flood when starting. the corrosion causes a higher resistance in effect changing the voltage seen by the ecm.

[Cliffy15]

I totally forgot about this post, but thought I should close this out just in case anyone else is having the same problem.

NISTECH was correct in his diagnosis of my problem. I changed out the coolant temp sensor and it solved all my problems. Thanks NISTECH!

I actually sold my '90 S13 and just picked up a '92 S13. But this sure is a useful bit of knowledge!

[KDashy]

You know, I'm having a very similar problem, but it happens very rarely(one out of every 50 starts maybe). I'll have to check that out.