- My model of MX-5 is: 1.8 NA '93, with '97 engine
- I’m based near: Devon
- I’m looking for technical help or recommendations on: Possible causes for engine popping, and what else I can check.
Hi all. Since a post I made a while back documenting everything from bad compression test results to an engine swap and issues along the way, I hope it’s ok that I’ve made a new Topic fresh with the one issue I have remaining, which should be easier for any helpers to navigate as the other was rammed with info and over 50 posts.
I’m getting an engine popping sound from idol and up through the revs, with the popping getting faster with the revs. There is no major misfire, and car seems to pull well, but the engine will judder every few seconds at idle. Here is a link to the noise being amplified through the air intake - https://youtu.be/376r1z7AxT0
Suspecting possible vacuum leak, I put my original '93 inlet manifold on to the newly swapped '97 engine, where there is now no potential ‘EGR blanked’ issue. I’ve put my original injectors back in, with new seals all round.
I’ve put in new spark plugs and new HT leads. I’ve tested the coil pack for ohms between each lead port (getting good results), but that is the only test on coil pack I have carried out.
I havent yet put my original throttle body on the new engine, however everything else (bar the engine) is how it was before the swap, where no popping noise was evident. The o2 sensor cable was on the exhaust manifold causing the sheath, which is used to keep the four wires together, to melt, but the wire insulation itself looks fine. Unplugging the sensor for a minute changed nothing, but I’m not sure if that’s normal or not. Compression test results were all good, at 180 each, but could it still be a leaky valve which isn’t being picked up?
I’m not sure what else I can check, and I just wanna get back on the road! Any help is greatly appreciated, and again I hope it’s ok that I’ve created a new post, but will add this to the old if it’s a problem. Cheers.