I'll save you the sob story about how this car is pristine and I've tried everything to fix it. It's low on power all around. It hesitates throughout the rpm band. The exhaust tone is not smooth, it's raspy and it sounds the car is working harding than it should. It is very hard to start off the line, as in normal driving off a stop light requiures a lot of rpm and clutch to make it start smoothly.

It's not a tuning problem, it's something either mechanically or electrically wrong with the car. What could it be? Where should I start? I have a feeling that it's a valvetrain problem but I wouldn't know how to diagnose it. I used to have comp Rs but I changed them out for stock lifters 1/4 past zero lash.

I'm sorry if this post was a little unorganized, I'm a wee bit drunk right now and I'm reminiscing about the days when the t/a was running perfect and it responded to a flicker of the muscle in my toe. Please help me fix this beast...

 

Could it be you have a dead cylinder or 2?

 

Does it idle? Vaccume hoses are always evil. Mine ran like hell when the vaccume hose was unhooked from the intake. I don't think this is your problem though because, there unbearable to drive with a vacume leak.

 

Could be just a sick coil or opti. You say you have "tried everything", but you don't say what...

 

I'm sorry I didn't list anything. I have found that when I make a long list of stuff people don't bother to read it and I don't get good responses. I'll make a little run through right now...

Flash back to a year ago. I just replaced the entire igntion system (opti, coil, ICM, plugs, OVC looms and wires). I was practicing launches near my old shop on my friends ET streets but I wasn't really familiar with doing a burnout on a 6 speed so I let my old boss warm up the tires. To make a long story short he basically banged the rev limiter for 30 seconds and destroyed my friends ET streets. After that, the car felt like a dog - almost exactly like it did before I changed the ignition. So keep in mind that the car ran perfectly from after the time I changed the ignition system to before the time I let my boss drive. Something he did fudged the car up.

Since then I've tried new lifters which I initially thought fixed it but it didn't. Then I put a delteq/plugs/wires on to just scrap the ignition system again and that didn't do it.

It does idle and I'm almost positive it's not a vacuum leak.

A dead cylinder is something I hadn't yet considered. I know that I need compression, fuel, and spark. Compression testing is a pain in the *** on this car though. What is the best way to test for fuel/spark?

 

so you changed valvesprings and then let him "bang the rev limiter for 30 secs"? I think this is probably your problem... Who installed the valvesprings, and what kind are they, what other mods do you have that required them? Slapping our rev limiter is a BIG no-no, I am sure you know this, but I have seen it cause a few problems if the valvetrain was not set up perfectly before you do this.

 

The springs that used to be in there were EX612s from combination motorsports. A couple months after the incident I had a spring break on me but luckily the car was just idling and it didn't drop the valve. I switched those crap springs out for comp 918 beehives . I haven't checked the install height but with the locks and seats I'm using it should be within .05" of 1.8". The valvetrain is set up correctly, I did it myself with the car off and with the car running with no difference. When I get new heads which will be soon I'm going to use double springs...

I know you guys are thinking you don't need to respond to this thread any more because I soled my own problem, the guy banged the rev limiter for 30 seconds... well believe me, I've checked the valvetrain, pushrod length and straightness, valve lash, changed to comp 918's and it made not a bit of difference. One detail that I did notice is that after that day the car made consistently lower oil pressure than it usually does. I don't know what that would mean, but now I get a max of 50 psi with 40 weight oil. Sometimes after I drive the car hard, it gets maybe 25 psi at idle, maybe 30 if I'm lucky whereas before it made 40 at idle and 60 at anything above 2000 rpm. Does that indicate anything other than wear on the bearings?

What really puzzles me is that the way the car feels now is almost exactly like it was before I changed the ignition system. It behaves similarly to before I changed all the ignition components, even though the evidence points to a valvetrain problem. How can I rule out the igntion system without using an oscilloscope? Also, how can I verify that I'm getting fuel and spark on all cylinders? Should I just ground the plug wires and check the spark out?

 

to check fuel you can get a noid light for it. that will atleast check the injector pulses from the ECM, next you need to check the resistance on each injector. If I am not mistaken it should be around 12+- 1. i could be wrong, but check them all and if you find one that is way off from the herd you might have a bad one. you can also pull the injectors and take them to Jiffy Lube or osmewhere and have them flow tested. As for spark, Advance sells 2 nice spark testing tools. One actulaly tests the spark gap distance so you can be sure that not only are you getting spark, but that it is also enought spark for the gap you have your plugs set to. The other tool is just a light that you plug in in place of the spark plug and just hold it in your hand and watch for it to flash.

as for the oil pressure, maybe his hitting the limiter caused the oil pump shaft to grind a few teeth out or warp or some other form of FUBAR.

Something I am curently tracking down started as a "stutter" that started around 2grand got worse until abotu 4-4.5k when the car would hit a brick wall and had absolutely no more power and sounded and felt like it was abotu to blow up. Replaced the opti and put in a Blaster Coil and the problem was eleminated to what it is now and that is a every so slight bog around 3800 until 4200. Well I pulled the ICM and COIL off the head becuase they were getting seriously hott (i dont have the A.I.R. bracket on anymore), and the problem seems to only happen when the car gets close to operating temp and hotter. This seems to have helped slightly. that oil pressure change seems to lead me to think that you might have a bigger problem than jsut a little heat issues.

good luck to you thou! I hope someone on here can give more insite

 

Have you really looked at the valvesprings. You do know that the 918s have had some serious problems, right?

 

Actually shoebox I was not aware that the 918's had issues. I'll do a search but is there anything specific you would like to inform me about?

 

918 failures have been plastered all over this forum and internet boards for months. I thought it was common knowledge by now. All you have to do is put "918" in the search box on this forum to find out.

ex. http://64.65.63.61/forums/showthread.php?t=526315

 

You could have bent a valve when your boss was bouncing off the rev limiter, or when you dropped a valve. I'm guessing you checked to make sure the pushrods are all straight? I'de start with a compression test and go from there.

 

Pull the valve covers to check the springs, no use in debating with someone if they're bent or not. Just check. Only takes a minute.

Compression check the motor. Pull all the plugs, and it's handy to have a few compression testers handy. Try to borrow a couple if you can. I did mine with 3 gauges. Faster than doing 1 at a time.

Post the results. If you have low or zero on one cylinder, you have a bent valve. To confirm, put an air compressor to that cylinder. Listen out the tail and throttle body. If you hear anything out the TB, most likely have a bent intake valve, tailpipe noise will indicate a bent exhaust valve.

Have you put a vacuum gauge on?

 

Wow. I did a search on 918's and looks like they are pretty ****ty springs. A lot of people break the top coil which is flattened to sit against the retainer. The springs appear to be weakest at that point. I will pull the valve covers and inspect the springs. I won't be surprised if I find some broken coils, since my cam has .577 lift on the exhaust side.

Are there any decent springs that fit stock heads and can be used if I upgrade to AFR's later on?

I have 2 compression testers. I will do a compression test as well and see what I find. I hope I find a dead cylinder because I hate doing plugs on this car.

 

LOL, yeah if pulling the head is easier than pulling the plugs. You do know to pull the head you have to drop the Y pipe, take the bolts out of the header, and pull the intake right? I mean it isn't that hard, but i'd rather pull plugs anyday.

The 918's are a great proven spring. There are so many people using them, of course some are going to be bad. There are a lot of people who got a bad set, but you might not be one of the unlucky ones.

918's is what LE uses and recommends. More people are using 918's without a problem than are having problems.