Jump to content
SAU Community

Recommended Posts

Hey guys, so I've put up with the problem since I bought the car but after writing it out I see how f**ked up it really is and it can't be normal.

My rs4 2.5T auto at light throttle it will rev to 3000rpm easily then stay there for a few seconds then go through the rest of the rev range slowly then reach 5000 and take off hard. Kind of like driving on flat ground then reaching 3000rpm up a steep hill and you reach the crest at 5000rpm

I've tried stock boost and 10psi but it doesn't make a difference. I was told it's a tuning issue, and i do believe him but I'm sure they didn't drive like that from factory because my old commodore had heaps more power down low. an old 90's Camy beat me until I reached 5g

I took the front drive shaft and the fuse and noticed If I do a burnout with no brake it will slide then take off slowly like it has traction controle. Even at speed and throwing it into a corner it will do this.

I've been searching for months for answers and I'm now at my wits end.

I've got a 3" from turbo to tail with split dump

I've replaced o2, coolent temp, afm, plugs 1.0 & 0.8, coils.

Link to comment
https://www.sau.com.au/forums/topic/427979-slow-to-rev-after-3000rpm/
Share on other sites

That does sound like a boring old misfire, particularly if you hearing it popping a bit at the same time it stops accelerating.

From your post you have already spent a heap of money swapping random stuff, why not take it to a workshop with a dyno? They can swap all the bits they need to without you buying and trying each thing.

If you want to keep trying the swapping you could always change the CAS and ignitor and resistor packs depending on what your engine has.

I don't hear any popping anywhere in the revs. Sorry should have said that.

I took it to Jez who found a fault with the afm and did a leak test while it was on 10psi. I do believe him when he said it needs a tune to fix the issue but when I changed the boost to the stock 2 stage the same problems occurred.

The stuff I changed needed doing anyway, just thought I should mention what I've already changed.

Could it be VCT not working properly? Or possibly hitting r&r even on stock boost? The power loss while trying to do a burnout is weird as they don't have traction control?

I need it fixed because keeping up with traffic can be a pain and I need to drop back gears and sometimes it will take off on me and is dangerous.

How do I check the cas, igniter and resistor packs Duncan? I've read posts where ignition and fuel pump are mentioned quite a lot. But no one posts after they fix the issue.

Jez also mentioned he removed my knock sensors and the only other fault was the afm which was changed also. I don't want to keep bugging him because I've done that enough

Not keen on burnouts, I would have bought a v8 if I did haha. I noticed it when I drove up a really steep hill in the wet and kept my foot down. It spun then lost power like it had TC. I then threw it into a corner and it did the same thing. I thought it might help diagnose my problem.

I trust Jez, he knows his stuff and has dealt with a few friends cars. But I can't afford an adaptronic and a tune to fix my issue

I was thinking it could be a tranny issue, the auto is in the ecu and never showed any codes, where's the solenoid for the auto?

no mention of ECU so I assume it's stock.

You've reset the ECU's or had them reset and checked for new codes without success

I'm no mechanic so I end up taking my car to the shop to identify and rectify. after I provide as much info as I can.

and yes if money is tight it's not easy I know.

Just from what info supplied above gave me a suspicion it may be more transmission related.

A tranny service wouldn't go astray for a few hunji dollars but could also not identify/fix issue.

(3.8lt auto commies spin rears easily - hence bogans fav drug delivery vehicles)

Thanks for the help guys,

I'll be checking my TPS voltage this afternoon,

I can't really check VCT, can I put it on stands and start it put it in drive then use the throttle from the engine to see if its clicking at 1500? Or is there an easier way?

And I'll search how to check my CAS

Doing more research, my 0v300 ecu will trigger r&r anything above the stock 5-6psi under 4500rpm which makes sense why it feels like a flat spot.(will hit 6psi stock) But doesn't make sense why I picked up very noticeable gains under 3000rpm.

Or/And

the exhaust has made a noticeable torque decrease while increasing the stock boost because it flows better.

Either way I don't think I can fix the problem without a tune or trying a stock exhaust.

Sorry early post""

They could if removed parts since last tune, thus making the car run rich or even lean causing the so called problems. I suggest a tune will quickly and efficiently resolve ur problem.

The ecu may be tuned already which will be the cause to your problem.

So I've been doing some driving and changing/checking things.

1. Boost T is coming loose.

I turned the T in 2 turns and the turbo spooled quicker, Had come half a turn loose again after 1 day so the turbo started to lag.

The T must like a certain position because it eventually went back to where it was, 2 turns looser.

2. The auto is getting confused.

Manually changing gears from 1 - 2 - D had a big improvement on getting passed the 3k flat spot.

O/D and Power didn't have any affect on the flat spot.

#2 would explain why it was happening on the standard 2 stage boost

I can now feel the small missfire at 3k on 10psi. I'll change plugs,clean AFM, box oil and i should be good to go.

Thanks for all your help everyone :)

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • You just need to remove the compressor housing, not the entire turbo. I would not be drilling and tapping anything with the housing still on anyways. 
    • So, I put my boat on a boat. First of all, I'm going to come out and say it. Why is Tasmania not considered a holy goal, an apex that all road-legal modified cars go to, to experience? This place is an absolute wonderland of titanic proportions. If people are already getting club runs for once in a lifetime 30 person cruises to Tassy then I've never seemed to see it. It is like someone replaced the entire place with an idyllic wonderland for cars, and all of the people living there with paid actors who are kind, humble, and friendly. Dear god. After doing a lap of almost all of the place I've found that it's a great way to find out all of the little things that the car isn't doing quite right and a great way to figure it all out. All in all, I drove for 4 hours a day for a week and nothing broke. I didn't even need to open the engine bay. This is by all means a great success, but it has left me with a list of things to potentially address. I also now have a 3D printed wheel fitment tool which annoyingly hasn't got any threads in it to actually assemble it. I might be able to tape it together to check the sizing I actually want to use, but it'll likely involving pulling the shocks out to properly measure travel at least at the front, and probably raise the car while I'm at it, at least in the rear. I scraped on quite a few things and I'm not sure how else to go about it. I was taking anything with a bump at what felt like 89 degree angles. And address those 10 other tasks. And wash the car. God damn it is dirty. And somehow, the weather was perfect the entire time - And because I was on the top of Mt Wellington it turns out it was very much about to freeze up there. I did something I typically never do and took some photos up there in what must have been -10 and the foggy felt like suspended ice, rather than mere fog. If you own a car in Australia, you owe it to yourself to do it.
    • Damn that was hilarious, and a bit embarrassing for skylines in general 😂 vintage car life ey. That R33 really stomped. Pretty entertaining stuff
    • Hi, I have a r32 gtr transmission. Does any of you guys have an idea how much power it will hold with the billet center plate and stock gearset? At what power level and use did yours brake with or without billet plate? Thanks, Oystein Lovik
    • Saw this replica police car based on a Mitsubishi Starion XX parked next to a 'police box' (it's literally a box) in Hirohata, Himeji City in Hyogo prefecture the other day. It's owned by Morii-san who is a local Mitsubishi Starion enthusiast. According to a local radio station blog post, he always wanted to make a police car himself based on ones he saw in his favourite Manga comics.  As it's illegal to modify a car to look like a police car and drive on the road, Morii-san tried many times to get permission from Aboshi police station headquarters nearby. They refused initially by after they got tired of that they granted him permission. However, the car can only be displayed on private property and obviously can't be registered as long as the police livery is present. The car was completed at a cost of 1.5 million yen (US$ 10,000) in addition to the car cost. A location was chosen outside Hirohata Police box where the car can easily been seen from the street. Morii-san has two other Starion road cars, both widebody GSR-VRs.
×
×
  • Create New...