Hi

I have found a 1990's CRX with a D16a1 engine installed for sale but when test driving it and talking to the owner of the car I found a problem with the engine.

As following, when starting cold it runs nice and smooth but as soon as it gets in normal operating temp it start having some problems with both idle and low and middle range rpm.

If i have the car on idle the rpm goes up and down but it never seems to stall just having trouble keeping a steady idle, but if I give some throttle it kind of stalling for a second or 2 before reving up. During the rev up period it dont rev smooth but it misses and choking abit, with some vibrations due to that.

But here comes the tricky part if I turn of the enginge and ignition and wait for a moment and starting it again it disappers for a while and the car runs smooth again, but after a while the same problem comes back.

The car runs smooth and nice in higher rpm over 3,5k, the car is equipped with a nitro system and ive been thinking if the problem could be connected with that in some way.
The nitrous tube isnt connected and I forgott to ask if they plugged the feed line for the nitro to the engine, could it be that it draws air thru that line, but if so why does it runs normal for a while when turning off and on the engine.

They also put in a open air filter solution but it seems fairly well done and leak free. The owner has put back the original exhaust system but as it goes smooth on higher rpm I dont think the problem can be related to that.

Please help me so i know if Im gonna buy this car or not.

 

To my knowledge, D16a1 is non-vtec, found in pre-90 Integras?
IACV could use a cleaning more than likely (Idle Air Control Valve)
might be the main issue, double check the engine stamp to the left of the exhaust manifold to see if it is truely a D16a1 or not, to my knowledge that swap sucks to even attempt in these chassis.