diggyd357

Here's a brief rundown...
I just bought an 04 RX-8 with 3,000 miles on a new rebuild. The previous owner also replaced plugs, wires, coils...did a cat delete....new starter....new battery....new solenoids..... He bought the car to make I to a drift car, but found out his wife was pregnant again with a 3rd child and made the decision to sell the car. Now I already know what you're thinking.... "Likely story for someone wanting to get rid of low compression 8". Only he gave me packaging, receipts, invoices and packing slips for all the parts that were shipped to his home around 5 months ago....So while I have not had a compression test done, at this point I believe him.
Now for my problem....
The car came with a random misfire cel and a cel for secondary air injection. The seller had the solenoid for the secondary air injection which I replaced day 1 and the code is gone. I did the ess reset and the p0300 random misfire went away also. Now...when I start the car it idles buttery smooth until that secondary air pump cuts out and then the idle goes to sh-t. It gets real rough , doesn't stall, but just an instant , very noticeable difference the second that secondary air pump shuts off. Then when I take off it drives what I feel is a little sluggish till around 4000 rpms at which time she flies. after 3 or 4 minutes of spirited driving the cel pops on. It still drives the same, but I don't wanna cause any premature wear or damage to the motor so I've just kept it parked. Well, other than the daily run I take so to not leave it sitting.
So what do y'all think ? I'm scheduled to have the air bag and fuel leak recall done on Monday and I was thinking this could possibly be a low fuel pressure issue . Im dying to hear what everyone here thinks. Thank you all for taking the time to read and respond. I'm thrilled to be a new 8 owner and a new member of this community.

CaymanRotary

Misfire usually related to the ignition (coils, wires, plugs and starter) or a clogged cat but the previous owner could have lied to you so those things should always be tested. If your ignition system checks out check engine compression. Even though it was recently rebuilt, it’s only as good as the guy who rebuilt it. How does it start when hot? The secondary air system should have no effect on how the car runs. All rotaries are sluggish under 4K rpm (gotta rev it!). The cel is likely p0420 related to your cat delete. Check the new owners sticky and welcome to the club!

NotAPreppie

What is the MAF rate at warm idle?

What is the LTFT at warm idle?

Have you tested the vacuum solenoids and actuators? Put a MityVac hand pump on the vacuum lines that go to the VDI, SSV, and SAIP vacuum actuators to make sure they aren't leaking. Same goes for the vacuum-side ports on the solenoids (the port that plugs into to the vacuum accumulator on the back of the UIM).

If you don't have a cat, the CEL is probably P0420 (like Cayman said) or P0139 (if they tried to use a plug anti-fouler tube to fool the PCM).

diggyd357

Thanks for the replies. The car starts fine when hot. The starter is new, but when he replaced it he didnt realize there was an upgrade ....so he went back with the OEM starter. So it starts slower than my truck does, but it's the same rather hot or cold. What's so strange is that it idles PERFECT for about 20 seconds everytime and then it goes to stumbling. I feel like it's a vacuum leak... I'm paying the $90 to the shop by my house to do a smoke test. I figure this should either reveal the problem or rule out a bunch. My other feeling is the fuel pump. Has anyone had the recall done ? Does the issue it fixes cause low fuel pressure? I'll update again once I have the results to the smoke test. Thanks again.

CaymanRotary

Jeez $90 for that? I just buy a cheap cigar and blow the smoke through a tube haha. When you get it back shoot a vid of your problem. It helps for us since we cant see or hear it.

diggyd357

Ckeared codes and drove it to work today (about 14 miles one way) . I didnt get a CEL until I was at work just about to turn the car off. The codes are p0301, p0300 and p0456. Gas cap is BRAND SPANKIN NEW BTW...

CaymanRotary

The p0300 and p0301 are misfire codes. Again, should be ignition or cat related. Could also do with your fuel trims if those are all in good shape. The p0456 is the purge valve solenoid if the new gas cap didnt fix it. Cheap part easy to fix Z504-18-741A.

diggyd357

New purge valve solenoid didn't help...still get the same codes. I did replace my coils and wires with the ones from BHR, but still have an awful idle. I did the seafoam treatment, still have a horrible idle. It's odd that it idles fine for about 20-30 seconds (sometimes a bit longer), but then drops down to just barely idling and sputters. I notice if I put my foot on the gas a little bit to steady it out then i can feel a constant surging... Surge then fall....surge then fall....surge then fall....and so on. If I rev it up and let off the gas it almost dies. It seems an awful lot like a vacuum leak. So I used a cigar and blew through a vacuum hose. The smoke only came out of the cold air intake where I pulled the hose from. I'm at a complete and total loss....

potatochobit

I bought new coil packs from some supplier other than mazda from autozone
and they lasted less than 10,000 miles

can you get more info on what coil packs he installed and how many miles ago?
I switch to D585 coil packs and car runs fine
but you could also have electrical problems

diggyd357

They're BHR coils....the best coils and wires money can buy. If you own an 8 and you're not familiar with BHR yet, check out the website or search BHR here on the forum. The owner seems to have devoted his professional life to figuring out , mastering and bettering the rx8. Not mention the time he spends helping others figure out their own RX8's. Not trying to be a commercial for BHR, but if you own an 8 you need to know Charles at BHR.
As far as electrical problems...yeah that's a good possibility. I have another post on the forum about my tachometer freaking out...like there's a bad ground somewhere. When I start the car it starts off pegged below zero . When it gets to 1,000 rpm it's really about 3,000 rpm. I used the tachometer on the torque pro app to figure that out lol. However I'm not convinced it's related as the misfire and stumble was there long before the tach freaked out. I did get new positive and negative battery terminals and cleaned up the grounds that came off the battery, but nothing changed. Still , I'm going to be looking at electrical more in the near future. I have a new clutch and transmission input shaft seal going in this week first.

NotAPreppie

That's not how you smoke test. You have to block off the air filter. The smoke will follow the air and take the path of least resistance. A proper smoke machine will also supply 5-10 psi of pressure to help force the smoke out of what is leaking.

You need to find the leak using good methods.

Also, which cold air intake?
Actually never mind that question. Just put the intake back to stock. Whatever it is, it isn't giving you the gains you think it is. The best you can hope for is that it doesn't cause any problems (i.e. AEM/MazdaSpeed or Racing Beat Revi). The worst may look like a vacuum leak because they screw with the MAF readings.

diggyd357

I pulled my plugs and cleaned them. I got a much smoother idle for a longer period, but still the idle changed and got all choppy again. It happens like as if a switch was flipped. It goes from smooth and quiet to BAM !!! loud and choppy. It still seemed to ride better after cleaning the plugs. The car runs excellent when I get on it. 1st and 2nd gear not so much, but once I got 3rd it puts you back in the seat. Those BHR coils made all the difference. Still gotta get this idle figured out.

diggyd357

diggyd357

FYI... It came on the car. I don't have the stock airbox

diggyd357

Ok, So i lucked up and found a car IDENTICAL to mine in a salvage yard. It had a complete airbox assembly so i carefully removed it, brought it home and installed it. I began reading up on the oem airbox and decided to remove the two side panels. Now Im wondering about the vfad... I already have the nipple by the throttle body plugged from when i had the CAI installed. Do i just leave the solenoid unplugged and thats it ? Or do i remove the fresh air duct too ? I havent put on my front bumper yet so it would be easy enough to remove, just need to know if i should.

**** Also, If anyone needs a Mazdaspeed CAI , PM me. Im not looking to sell it, but if this stock airbox turns out to be the answer to restoring my idle Id be willing to give it to whomever wants it as a THANK YOU for your help and your time.

Thanks !

Loki

iTrader: (1)

The VFAD is open by default so you can just leave it unplugged. As long as there are no holes in intake anywhere after the throttle body, you'll be fine.

I'm a little confused by what you're say about 1st and 2nd gear not accelerating as much as 3rd. Logically 1st is the gear with highest acceleration, followed by 2nd, etc. Is your clutch slipping, possibly?

What are your fuel trims on a warm idle? That would give us pointers on where to look.

diggyd357

Clutch is definitely slipping. I ordered an Exedy clutch kit from BHR and have the transmission out as we speak. We found that My old clutch was damned near new. It looks like it was probably recently changed. I have a other thread all a out the clutch, but basically i had some rather pronounced slipping during spirited driving along with some oil spots on the concrete wherever i park the car. Then to top it all off, i went to change transmission oil and only aboug a quart of oil came out when i drained it. So i assumed the input shaft seal was leaking and wetting the clutch. Now that we have it apart, the input shaft seal looks to be dry and the rear main seal seems to be the culprit. Obviously both seals are getting replaced, but im left wondering where the hell the rest of the transmission oil went.
Sorry to drift so far off topic. So back to my original question .... You say i should leave the fresh air duct in place ? Is there ANY benefit to removing it? Becasue like i said, my bumper is still off so its just one bolt and one clip and i can have it off in a second or two.

Edit :; As far as fuel trims.... I dont have any way to get that info for you.

Ricky SE3P

iTrader: (10)

Might also be worth looking at your front O2 sensor... I recently was having a lot of problems and could not find the source of the issue after replacing my engine. Turned out my front O2 was giving slightly inaccurate numbers to the computer, and the car was misfiring trying to correct fuel trims based on the inaccurate data the O2 sensor was telling it. Switched it out and everything went away.

diggyd357

You didnt get a code specific to the O2 sensor ?

Ricky SE3P

iTrader: (10)

No I didn't.

I replaced all my coils, wires, and plugs (twice for each of those). I replaced all 6 injectors. I replaced my MAF, my ESS sensor, all 3 intake solenoids, did the 20 brake pedal stomp countless times. I would get misfire codes, never once got a front o2 sensor code. Drove me crazy for about 3 weeks, replaced the front o2 in about 8 minutes and everything went away. I was annoyed as hell.... happy, but annoyed. Something so simple caused so much headaches, so its worth giving replacing it a shot.

diggyd357

No doubt ....
Thank you for taking the time to chime in. I will absolutely keep this in mind and if the air box doesn't do it then I'll run by the dealer and grab an O2 sensor. Thanks again !