Low RPM idle and acceleration?

BRANDON SIPPL

MEMBER
1990 MAZDA MIATA
1.6L
4 CYL
2WD
MANUAL
165,000 MILES

I purchased a 1990 a few months ago and replaced the engine. This is my first time doing an engine swap and the low rpms have been holding me back for a while now.

Here's a video of the car running at less than 500 rpm during idle and barely reaching 1000 with full throttle:

https://www.youtube.com/watch?v=FLmT...nnel=shipupuru

The only new parts other than the engine itself are the battery, starter, MAF, filter, and hoses/vacuum lines.

I've cleaned multiple parts that could potentially be the issue. This includes the throttle body, IAC valve (new gasket), intake manifold, fuel injectors, o2 sensor, and the TPS.

I've done a lot of research but haven't had any success yet. I've been debating on purchasing a new throttle body, but I wanted to reach out for help before I spend any more money.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

I tried to watch the video, but it indicates that it's no longer available. See pic below

Next, have you checked for diagnostic trouble codes? This vehicle has an OBD1 system that doesn't require a scan tool to retrieve codes. Here is a link that explains how to retrieve codes:

https://www.2carpros.com/articles/diagnostic-trouble-codes-for-1995-and-earlier-mazda-cars-obd1

Next, make sure the catalytic converter isn't clogged and causing this to happen. You can remove one of the oxygen sensors to see if things improve. Also, take a look at this link and let me know if anything mirrors what you are experiencing.,

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

Let me know.

Joe

See pic below.

Image (Click to make bigger)