Loss of power 4.5k to 6.5k revs

[Davemitch]

Ok, had this ongoing problem for the last year and cant solve it!

As title, I have a poss of power 4.5k to 6.5k revs, power is perfect either side of this, surges on both ends of revs. Its had a replacement engine ( 7s both rotors) where everything was taken from donor car and put in to mine, had standard wheels back on, its decat, and coils replaced as well.

When hitting 4.5k revs and upwards, there is a definite smell of oil which makes me think a vacuum leak or oil leak on pressure somewhere? I just don't know where to look!?

When replacing engine, engine was known to be working very well and compression tested by Dean (member on here) and ssv and everything was all transplanted over together.

Please someone give me hope Haha

[HypoThermia]

Someone more knowledgeable will be along in a moment, however that rev range is associated with the second port opening up. Possibly a problem with the fuel injectors being blocked?

[MarkG M3CP]

Sounds like a solenoid - similar to what happened the the Car Throttle car?

[Davemitch]

Someone more knowledgeable will be along in a moment, however that rev range is associated with the second port opening up. Possibly a problem with the fuel injectors being blocked?

Fuel injectors were also swapped from the known working engine too, I thought this as well, it's the smell of oil that really makes me think

[Davemitch]

I'm even swaying towards fuel pump now maybe?

[Davemitch]

Sounds like a solenoid

I'll take a look at the video now, just not sure with the oil smell too

[MarkG M3CP]

More smell than a regular decat or premix?

That’s what prevents me going decat!

[Paul_13]

I'd check the injector wiring. having the plugs going to the wrong injectors will cause a similar issue. Also the VDI and Aux ports open around this rpm.
You need to check the solenoid vac lines from the back of the inlet manifold to the VDI/SSV actuators. Also check the Aux port motor.
Might be worth buying a vac pump test kit.

If you get a minute have a look at my build thread on mazda rotary club forum, i detailed a lot of this.

http://mazdarotaryclub.com/forum/index. ... =84712.555

[Davemitch]

More smell than a regular decat or premix?

That’s what prevents me going decat!

Oh it's always stank of fuel, first mod I did was decat lol but over 4.5k revs and stinks of oil now and it's only done that since this problem in new engine

[MarkG M3CP]

More smell than a regular decat or premix?

That’s what prevents me going decat!

Oh it's always stank of fuel, first mod I did was decat lol but over 4.5k revs and stinks of oil now and it's only done that since this problem in new engine

Ha!

And have you had the upper inlet manifold off yet to check for contamination all the way through? Sounds like it could be a pressure (or lack of it) issue - vacuum wise.

Again, I think the three solenoids play a part.
Annoyingly I binned a load of spares recently but you can pick up an entire upper manifold for £20 ish.

[Davemitch]

More smell than a regular decat or premix?

That’s what prevents me going decat!

Oh it's always stank of fuel, first mod I did was decat lol but over 4.5k revs and stinks of oil now and it's only done that since this problem in new engine

Ha!

And have you had the upper inlet manifold off yet to check for contamination all the way through? Sounds like it could be a pressure (or lack of it) issue - vacuum wise.

Again, I think the three solenoids play a part.
Annoyingly I binned a load of spares recently but you can pick up an entire upper manifold for £20 ish.

What's annoying is the perfect running engine was completely put in including the manifolds as well. I'm swaying to these solenoid I think too

[BigPete]

The air valve on the side of the intake opens between those revs, so either the solenoid or it’s stuck. Try moving it by hand first and if it moves easily then it’s the solenoid at fault

[Davemitch]

Had a play with Torque app and I think this graph best shows the problem. Now changed wheels to standard, intake to standard, ignition is rotary revs d585s, racing beat dual resonated decat and hks single exit. Full engine and ancillaries swapped from mid 7s compression known running perfectly last year, can not for the life of me find this fault

[PaulAV]

Just had similar problem with a noticeable drop of power above 4k to around 6.5k, there is a small vacuum link pipe under the throttle body /uim that can become dislodged when doing anything near the oil filter, worth checking, also in some cars where you have your service nipples there is a vacuum pipe attached via a T- piece to both nipples, I find a small hole in one recently just past where the pipe pushed on, so I cut about 1/2 inch of pipe off and it was all good.

[350matt]

agree that it sounds like a faulty solenoid to me

[Nerdstrike]

Just checked my old plots - two fairly standard 231's were pulling in 150-160 g/s through the MAF at WOT and 6k RPM. The peak should be north of 200 g/s give or take. Note Phil B and others' protestations that MAFs are not callibrated w.r.t. each other, but the numbers shouldn't be wildy different without major fettling/porting/boosting.

I know for a fact my car had worse compression than yours and was in the 6's when I took the data. Maybe it'll help you know if you've fixed it.