The car is a built block peak boost 35r 03 viii. All the basic bolt ons, Buschur double pumper, AMS FPR Kit, RC 1200cc inj's, AEM 3.5bar map sensor. The car drives great, idles great, with perfect compression numbers, but with a hiccup after 5k RPMs.

I know that prior to building my motor, the car would do the same thing that its doing now. From 2500-5300 perfect, and as soon as boost starts ramping up it would have a hiccup for 2-300 RPMs and then back to perfect again. I have to many data log files that I can supply to anyone interested in taking a look.

Thought it was spark plugs, changed them 3 times with different heat ranges and gaps. We thought it was the FPR on its way out so we got an AMS fpr kit. The issue only lasts for less than a second but the AFR goes rich and it stutters slightly then pulls hard again. Here are the things we are thinking of testing/trying now:

- I would assume that the AEM and the sensors are ok, but both would need to be investigated.

- It would be worth checking to make sure the trigger wheel on the crank isn’t damaged (I doubt this is the case since the signal errors aren’t consistent)

- It could be anything ranging from: wires crimped, broken wire inside insulation, electrical interference requiring a filter to filter out the noise (I’ve seen this on Scion TCs with AEM FICs).

Any and all help with this issue would be greatly appreciated. I am hoping to find someone that has had an issue like this that can offer some advice. I am going to post this here as well as in the AEM EMS specific field. Thanks all in advance as I just want to get my tune finished. Car has been sitting for nearly two months now while trial and erroring on it.

 

me and my friend are both thinking about aem ems for our evos. i have a nine, and his is an evo eight. do u recommend this ems?

 

This topic is about getting help. On a side note, yes I do. I would be prepared to get a beefier ignition setup depending on your power goals.

 

Try swaping out the Cam Sensor with one that is know to work or a brand new one.

Had the same problem with a customers evo and I changed 1 thing at a time and when I changed that it cure it. You should invest in a cam sensor heat sheild if that turns out to be the problem.

 

Going to test this and see what we get. Thanks again all and any advice/suggestions is greatly appreciated.

 

Didnt have the chance to get the EVO on the lift today. Hope to get it up tomorrow to check the sensors.

 

what does your a/f reading look like when going through this region?

post a log if you want.....need to put it in a zip file.....

 

We experienced the same thing on one of our customer's car it was a fully built 2.0L evo 8.

We thought it was ignition break up and tried multiple sets of coils, plugs, gaps, etc to no avail.

Then we even took the AEM out and sent it back to them......they sent us a new box and it didn't cure it

So we ended up swapping the "cas" and it did the trick.

I hope it's that simple for you

 

Purchased a Crank Angle Sensor from the dealership today. Hoping to get it in tomorrow and see if it takes care of the issue.

 

Wait "crank"

We mentioned "cam" angle sensor

 

Replaced the crank sensor, re-sealed the oil pan and its working perfect after 5 pulls this morning. I will keep all posted if it fixes it after another 5 pulls today.

 

Crank sensor fixed the issue. Next issue came into play. Couldn't go over 26psi...ended up being a tear in my main line off the intake manifold. Got that fixed and then the next issue comes into play......(at this point I am starting to dislike my Evo)the dyno plot shows that it ramps up about 30-40hp above what it should be at(spikes) and then falls back to normal. We thought it might have been the clutch slipping, but then it went away and didnt come back for 15runs. The entire time though the power was up and down. One run would be 490, the next 550, the next 515, the next 540, next 500....it was very inconsistent.

 

Bro my car started doing the exact same thing "hiccuping" my friends are like bro your taking your foot off the pedal. Waited awhile started accelerating bam same damn thing. Thanks for the info keep me updated on it though I'm taking my car to the shop tommorow we thought spark plugs as well!~

 

Everyone told me cam sensor, but it was the crank sensor for that issue. Now I am having an issue getting consistent dyno runs. My car seems to spike in power and then drop back down. It does it some times but not every time. I am going to have my tranny off next weekend to rebuild as well as front dif. While in their I will be checking out the clutch.