2.3 dies at 5000 rpm.

[87covertible2300]

Hello, 

Im Josh, new here recently picked up a 87 convertible fox that was 2.3 turbo swapped out of a salvage yard. It was full of stinger parts! couldn't pass it up even tho its a vert. Long story short car went from stock to fbo lol, pimpx ecu, spartan 2 lambda, gutted 120 intake mani, tc 60mm tb, stinger fmic kit, 630cc dekas, fuel cell w Bosch 044 pump, made a exhaust mani and bolted up a hy35 and a tial 44mm, mild cam can't remember specs. just about everything came in the car or I had laying around my house. 

Now to my question, got all my pimpx settings in and dialed up the idle. started working the fuel maps with tune analyze, everything was looking good starting at 10psi. Car runs great, idles and drives as should but as soon as I get up to 5000 rpms the car just falls on its face, starts misfiring almost like hard fuel cut then just seems to run on 3 cylinders, sometimes stall and afr's get super rich 10.8-10.20. then will start running fine again if you keep it running or give it 10-15 seconds before restart then afr's go back to target afr and car runs completely fine again. car does this in all gears every time like clockwork easy to recreate. afr's are good at wot 11.5- 12.1 till it misfires. at idle with quick stab will get a map sample error and it is hooked up as recommended don't know if that info helps or is even a big deal. will sometime get tps fault on ecu but goes away and sensor works good on gauge, have not tested sensor though. read that this is the place to get the quickest answers, poked around on here searching to see if this topic was on here and couldn't find anything. just curious if anybody has encountered this issue or might know a direction to start diag instead of a total wild goose hunt. 

also curious what this setup might make (never played with 2.3's, but have boosted a couple 22re's on ms3 n it was always a let down lol)

thanks,

[Stinger]

Sounds like weak valve springs allowing the lash adjusters to overfill and hold the valves open at high RPM. This causes the misfire and after the oil has time to bleed off the valves close and it goes back to running fine.

How much power depends on boost level, fuel octane, and condition of head & valve seats (most old heads leak at the valves).

[87covertible2300]

it does this unloaded or loaded, with 10 psi or 4 psi. I ran this car on the stock ecu with stock charger with 15 psi and the car had no issues over 5000 rpm. I can rev it in place to 5000 rpm and it will run bad then randomly clear up after a few seconds. the cam doesn't require springs either, I don't believe it to be a head issue, is there anything else that would cause this. it has upgraded lash adjusters  as well, the tach itself is about 100 rpm different then the rpm on the ecu don't know if that matters some people say it does or doesn't. if it is the valve springs thanks, just curious if anything else is possible. 

[Stinger]

It's got all the textbook signs of weak valve springs. The two main symptoms are that it's RPM dependent, and it runs poor for a certain amount of time after the problem (whether it's still running but missing, or won't restart immediately after). Without a datalog of the issue happening, and a copy of the tune, I have no reason to believe, or any way to see whether it's possibly anything else.

[87covertible2300]

I did some rechecks on things I've done to the car that could cause communication issues pertaining to this issue, I have no ecu commands or faults so I poked around on here about other threads you replied valve springs too and I agree at this point. ill upload a data log and tune file anyways. but is there any valve springs that are a good bang for your buck that are drop in to get some extra holding pressure? or is it possible to install 351 springs in it? I have a full set of dual 351 springs. I plan to smack this thing with 25-27 psi so I'm assuming I'm gonna need extra holding pressure lol

[Stinger]

Is it a roller cam? Roller cams can handle a lot of spring pressure, slider cams you basically want to run as much as you need but not more.

What springs will be best depends on the cam specs, whether you are willing to machine the head or not, roller vs slider cam, etc. Many springs require head machining (especially dual springs).

[87covertible2300]

its a roller cam motor, I installed 110lb dual drop in valve springs with .30 shims kept head on. the springs were cheap and I figured it would work fine with my setup right now. totally fixed the problem! I have the car on 15 psi right now and run out 6200 rpms, runs killer. its on 93 and plan on turning the boost up a little more. 25ish lbs is my goal even if it doesn't last terribly long, but after reading around doesn't seem to be an abnormal number to achieve. I read multiple threads where you (stinger) talk about pre det a lot at higher boost levels on 93. so my question is would it be beneficial to run e10 or e20 blend to be safe from knock, will my injectors flow enough at 25 lbs to handle a blend of e10 or e 20. also I have vac line to ecu tied into ref for fpr, I'm not running iac and am having trouble getting car to idle smooth. would it help to run the ecu to its own port or is that not a part of my problem. I have smoke tested car for vac leaks.

[Stinger]

Good to hear it fixed it.

25 lbs is a lot on 93 octane. Might be able to get away with it in cold weather. You won't know if you've got enough injector for it until you see what duty cycle is at high boost. Without a datalog, I have no idea but my guess would be you'll run out of injector.

I can't comment on what's causing the rough idle without seeing a datalog of the issue, and a copy of the tune. These can only be posted in the PiMPx section, not here.