So I start my car this morning (30 degrees) and the engine revs up to 1500 as usual for warm up and then after a minute, it starts spitting, popping, and running rough like it only some of the faces are firing properly. I am a new owner and have minimal experience with them. I have done searches and have come up with TPS, MAP Sensor, Items that should have not have changed while sitting overnight. I just need some good places to start. thanks

 

list mods, mileage. what happens when the car warms up? is it only when cold? if it is only when cold, i would suspect the idle speed controller.

 

O2 sensor....after it warm up, it goes to feedback mode.

 

with minimal experience, you should take it to a professional. Otherwise, you're gonna spend a lot of money replacing this & that. Or even make it worse.

 

I have a ton of mechanical experience, but this is my first rotory, new to RX7 not cars.

 

140K
PFS Intercooler
3" Downpipe
3" Exhaust
AST

I have not let it warm up yet. Also the coolant fill bottle is cracked and doesn't hold coolant (fixing). The Low coolant Lite came on when I started the car. I imidiately turn it off and filled the coolant. Lite turned off and then this problem started.

 

do you have a long peroid of coolant smelling white smoke at start up?

 

did have some white smoke on start up, the owner that I purchased it from said the engine needed a rebuild and had 8.5 compression accross the board. I have not pulled the plugs yet to see if coolant is leaking into the combustion chamber, I have not had a ton of time to look at it with work. I appreciate all of your help.

 

Changed Plugs and check TPS, and the car is still acting up. Here is the Exact sequence of what happens.

Start up is normal and smooth at 2k
engine winds down to 1.5k and starts running rough from their

 

Check your ground wire contacts. After heat soak begins, your contacts may not be as efficient as when cold. You need to use sand paper or a steel wire brush to get rid of any corrosion build-up. Even the smallest amount affects the ground contact. You have three ground contacts to check: one at the firewall behind the UIM (towards the passenger side), one on the driver's side fender wall just below the fuse box, and one down below on the driver's side of the engine block just above the oil pan lip (you can reach it through the engine carriage framing). When the ground contacts get corroded, the car will not run even. Everyone has had it happen sooner or later so do not feel exclusive. Hope this helps.

 

Check your ground wire contacts. After heat soak begins, your contacts may not be as efficient as when cold. You need to use sand paper or a steel wire brush to get rid of any corrosion build-up. Even the smallest amount affects the ground contact. You have three ground contacts to check: one at the firewall behind the UIM (towards the passenger side), one on the driver's side fender wall just below the fuse box, and one down below on the driver's side of the engine block just above the oil pan lip (you can reach it through the engine carriage framing). When the ground contacts get corroded, the car will not run even. Everyone has had it happen sooner or later so do not feel exclusive. Hope this helps.

 

Have you let it warm up all the way? So the idle comes down to 850 or so? Does the idle smooth out when warmed? I ask, as there is another thread asking roughly the same thing. All stock ecu cars seem to have a rough idle when warming up, typically starting about 1 minute after start up, and lasting up to 2 minutes. then the engine idle smooths out. I usually let it shake rattle and roll, then drive the car after it stops this. It does this less on warmer days.

 

https://www.rx7club.com/showthread.p...hreadid=294155


also, with 8.5 comp across all rotor faces... thats DAMN good.... why did he say it needs a rebuild?

 

Absolutely! If this is all you are experiencing then you have nothing to be concerned about. The idle control valve and the water thermosensor are just having a mini-battle when the engine is warming-up. When the engine is cold, the water thermosensor is telling the ECU to keep the rpm's up to warm the engine, while the idle control valve is trying to restore idle to the proper settings, i.e., between 750 and 850. While this battle is going on the engine pops and stutters trying to deal with the conflicting signals. It's just normal.

 

Still rough! It is like a 4 cylinder running on 3 cylinders only.

 

Sorry I meant 7.5

 

This is the way it used to act, now it is much worse and does not smooth out. It warms up, idles down, all the while spitting and sputtering. I noticed black smoke out of the exhaust, as if it is dumping unburnt fuel out of the exhaust.

 

I noticed a similar idle problem this morning too, I just disconnectd the ISC and it seems better now.

 

Then did you check your ground wire contacts as I originally suggested (see earlier post)? The smoke simply means your idle settings are not right. The problem is finding where.

 

Thanks for all your help, but I figured it out. I had one of my mechanics at the shop take out the intercooler and clean it out, along with the AST. When he reassembled it he unknowingly pinched the waterline from the water neck to the AST. Its amazing what a small pinch will do.