Cold start/take off stalling/stuttering with e30 down on Power

[JinormusJ]

So my m20 likes to stutter at cold starts. When I take off, it'll drive normal, and then seconds after driving, it will lose all power until I give it a little more, then it jumps and drives normally. The car will also stall/stutter at stop lights or before takeoff (I will give it gas, but the TPS won't sense the Throttle is on until a second or so after I've given acceleration.) Stalling doesn't happen all the time, but it will stutter every time from a red light. At WOT, it will smoothly climb the revs, only it is very very..... slow... like an m42, which leads me to believe I am also down on power; don't have the nice low end torque an m20 is known for.

I don't have vacuum leaks; I just replaced all my vacuum lines/intake boot and my idle is never too high or low

My ICV is good as I do not have oscillating idle issues

I have not checked fuel related items (Fuel lines, FPR, Fuel Rod, Injectors)

From what I've gathered; I figure either my AFM/TPS or my FPR/Fuel Filter/Fuel Lines are the problems. They have not been replaced/serviced in probably never, and my problems seem to be all throttle related, indicating either an air or fuel issue.


Any input on where to begin r3v?

[EatsHondas]

Does it run like this all the time or only when cold? I'd pull the plugs if you haven't already and see what they look like.

Also, replace the coolant temp sensor. It's cheap and is the common culprit of a misbehaving e30, especially when cold. Get BOSCH, not FAE or any other knockoff.

[603Racing]

Other things besides vacuum lines and intake boots will cause vacuum leaks. Bitch tube, valve cover gasket, intake manifold gaskets, just to name a few. Get a smoke test done.

However, I'm with EatsHondas, if it's only doing it when cold you could start with the coolant temp sensor. Then get a smoke test.

Doesn't sound like a fuel pressure problem, but you could check the fuel pressure. Then get a smoke test. :)

[JinormusJ]

I've replaced my VCG, and performed a smoke test already and there are no leakages.. I can guarantee you 100% it's not vacuum leaks; I know what an idle with vacuum leaks sounds like, and it's definitely not it


I was just wondering if it was a fuel issue because my engine is down on power. The stuttering is not a problem, but what really pisses me off is that the m20 isn't putting down as much power as it should; kinda like the AFM is clogged and it's struggling to get air into the system.
The cold start stuttering is a side effect from whatever is affecting the engine.

Let me clarify though; it doesn't idle differently while cold, just stutters at the first start, but does not do it anymore once the car has been started that day. I can check my sensors though; they are pretty cheap.


I'll pull my plugs tomorrow and see what they look like; from what I remember from last time pulling then, they looke okay but we're a little black. I'll see

[603Racing]

Good deal on the smoke test. Check the fuel pressure at idle and while driving.

Does the power get better when the car warms up?

Backing up a bit, did it just start this all of a sudden? Did you make any changes to the car before it started doing this?

[JinormusJ]

It was always doing this and nothing I did seemed to make my throttle response and idle better. I'm more concerned about my stuttering/stumbling at stoplights as that has lead me to stall (in a automatic too!) in the middle of a green light.

I'm going to source a known working AFM and go from there; if its not what I think it could be, I'll start checking out other problem areas