"Choppy/not smooth" acceleration prior to boost or 3000rpm

[2007BlackSpeed3]

Hey Everyone,

So I've been doing a way ton more research and bought the beginner's guide to modding mazdas by corksport. Just trying to not keep getting flamed for not doing research lol. So.. I have an issue with my 07 MS3; all it has is an exhaust, nothing else. It's hard to explain (and I've searched on this forum and Google and can't find anything).. But in slow speeds, prior to 3000 rpm, the acceleration is very choppy.. Like not smooth at all. But once u hit boost or go over 3000 rpm, everything is normal.

Does anyone have any idea what I'm talking about?? I'm lost here.. Thank you and plz don't flame me I really tried looking myself!!

[MSMS3]

What do you mean by “slow speeds” and “choppy” acceleration?

Does it idle smoothly in neutral? What is idle rpm? Does it misfire when you rev it up in neutral? Does it do this in any particular gear and accelerator pedal position?

You have a Cobb AP? Read how to data log with it. Then post a log. That is the first step in diagnosing things like this. Without data it’s impossible to diagnose those vague symptoms.

It’s like asking a doctor to diagnose a disease over the phone by saying only that you have a cough.

[2007BlackSpeed3]

It idles smoothly in neutral. No misfires when you rev it in neutral.

It pretty much does this in every gear, as long as you are under 3000 rmp.. it's almost like it's bogging.. my theory is that with the exhaust it's "air" or "back pressures" being messed up?? I have an accessport, but that it installed in my other MS3...

[Db09ms3]

Have you done a tune up? What constitutes an, 'exhaust'? Need more deets sucka

[2007BlackSpeed3]

No tune.. It just has a setback (Cpe)..

[Db09ms3]

Cool. Okay, not a tune but a tune-up. As in spark plugs, gapping, etc. Have you done that? With any used car you buy you should at least get that out of the way first. I hope you know how to wrench

[2007BlackSpeed3]

I've changed spark plugs on my Honda, but never worked on a mazda before. Gonna do an oil change and spark plugs in the next two weeks.. Hopefully that takes care of it!

[Db09ms3]

Scrub, get on that maintenance! It's just an engine, treat it as such.

[2007BlackSpeed3]

U guys really think it's the plugs?? I thought maybe it's cuz of the exhaust that's like throwing stuff off,,,

[Db09ms3]

Get to work and report back. If anything, just pull them, clean and re-gape them.

[MSMS3]

Originally Posted by 2007BlackSpeed3 U guys really think it's the plugs?? I thought maybe it's cuz of the exhaust that's like throwing stuff off,,,

Exhaust would be the last thing on my list.

[MSMS3]

Originally Posted by Db09ms3 Get to work and report back. If anything, just pull them, clean and re-gape them.

Don’t try to clean iridium spark plugs. The fine wire center electrode has a very thin plating of heat resistant iridium. Cleaning will likely destroy that. Regapping must be done very carefully for the same reason. If you scrape against the tip of that center electrode, the iridium is gone. Use a gapping tool that only moves the ground strap without touching the center electrode and feeler gauges for measuring the gap.

Probably best to replace with new NGK, stock heat range, gapped to .026”.

Check for dirty air filter, too.

[2007BlackSpeed3]

so I actually took a good look under the hood today... I replaced the battery to a 35a cuz it was only a 25a before and it was 6.5 years old and dying..

it actually has a CPE engineering cold air intake.. and exhaust..

I ordered the spark plugs a few days ago.. I did not get NGK though.. I got the DENSO (5340) ITV22 Iridium Power Spark Plugs.. and my plan was to gap it to 0.028.
You think that will be ok? I DID do my research and though that was the best route to go...


LMK your thoughts, THANKS!!!!

[Db09ms3]

I got the denso ITV20's (5339) gapped to .028. I think you got the step colder ones? Someone else can confirm. Gap them and try it out

[MSMS3]

Get stock heat range. You have to be at or near +100 hp above stock to need one step colder ones. At stock power levels they may foul and cause misfires. You always want to run the hottest heat range plugs that do not cause detonation and the coldest that do not cause fouling. In this instance, that means stock heat range.

Gap is now recommended to be in the .026” range, and as tight as .024”. Going .028” with colder plugs is just an invitation for fouling without supporting power mods.

[2007BlackSpeed3]

Thank you for the input, always appreciated! Dangit I just bought the one step colder plugs...

[aaronc7]

CPE Setback.... that's a better name for it

[2007BlackSpeed3]

Lol?! What's wrong with the cpe exhaust..

[MSMS3]

Originally Posted by 2007BlackSpeed3 Thank you for the input, always appreciated! Dangit I just bought the one step colder plugs...

You can try to use them, but they are not correct at that power level. If you do, gap them pretty tight. .024”-.026”. If they foul, get normal heat range.

[2007BlackSpeed3]

well I did the sparkplugs today.. feels a bit better overall, but the "choppiness" is still there at low speeds.. its very hard to describe.. I will try to get it to a shop in a couple weeks to do an oil change and see what the CEL's are on for..

It does have a CAI and exhaust so I wonder if its not getting the right air/fuel ratios..

[Vansquish]

The CAI is probably your problem. If you have an intake with a larger-than-stock MAF housing, or a MAF housing that doesn't have an air-straightener in it, then your MAF will not properly report the quantity of air entering the engine. This will cause the ECU to attempt to compensate by adding fuel, measuring, removing fuel, measuring, etc. and will feel like stuttering or choppy acceleration.

In all likelihood, you need a tune that is customized for the modifications on your car.

[Jeff23spl]

If you have a cel, of course start by reading it.

I'm just not sure about your description of the problem, have you checked boost level during that problem with your AP? Can it be overboost cut while you try to load the engine at low rpm in high gear?

[blackmica6]

Also, check the camshaft position sensor. Mine was going bad and it started to infrequently have a choppy acceleration on low and high RPMs alike. Changed it and the engine runs smooth now. I'm no expert, but the camshaft position sensor is easy enough to get to.