FreeSpirit

Anyone know what this might be? If I floor the gas pedal, the RPMs will go up pretty slowly. The pedal will be floored and the RPMs will still be going up slowly from 2500. Sometimes after a few seconds, it will suddenly shoot up fast up to 5000 like it's supposed to.

However, in park, it revs perfectly, and revs up much faster when I floor it. Like it will reach 5000RPM almost right away, like it should. Instead of slowly climbing up like it does while in drive.

Work done in the last 2 years:
- cap, rotor, wires, plugs, coil pack
- Ignition control module
- all vacuum lines replaced, including the ones that are easy to miss like evap canister, the weird vacuum ball at the front driver side, the ones near the EGR valve
- fuel filter
- Throttle position sensor
- IAC valve, also set it properly using the procedure I found on this site
- MAP or MAF sensor (forget which one we have)
- Coolant temperature sensor
- full exhaust: headers, y pipe, cat, catback
- more that I can't think of right now

I posted my first data log here: https://www.thirdgen.org/forums/dfi-...a-log-can.html but it was just at idle. I'll try to get one while it's running soon

FreeSpirit

Here are some data logs of it driving at WOT. Still haven't figured out the problem.

SparksAj

I'm not the smartest and really just throwing one out there, but could that be the transmission slipping? Would it really shift in park? Check your fluids? Again, not the smartest, but maybe?

someone972

iTrader: (2)

Maybe try the adjustment procedure for the TV cable? I don't know if it would do anything but since this thread is pretty quiet just throwing it out there.

FreeSpirit

Fluids are all good. I'm pretty sure the transmission is not slipping. It doesn't feel like it. The engine just revs the same at WOT as it would at 50% throttle. The RPMs go up slowly, but the car is still pulling.

NCC-2569

iTrader: (1)

Without being able to look into those logs from here, does your TPS produce a linear increase in voltage when you slowly push the gas pedal down or are the values jumping up and down?

From your description I would guess this is an ignition timing issue.
How did you set your timing back then? Did you remember to disconnect the EST?
I remember that flooring the pedal made almost no difference as I test drove a badly set car.

How does it FEEL when it revs up so slowly?
Is there any chuggling or is it smooth? What's it feel like when it suddenly goes up to 5k rpm?

Also check the hint about the t.v. cable.
If it's badly adjusted you can have the strangest shift points and let's say the car goes into second or third gear much to early.
The engine would have difficulty raising speed until it reaches a certain point.

FreeSpirit

Yes, I disconnected the EST. I double-checked the timing recently in the past few weeks, too. It's still at 0* which is what my RS hood says is stock. But I did put headers and full exhaust on my car, so maybe I should bump it up a little? I put 87 fuel in the car.

The logs do not collect data frequently enough to show if the TPS voltage is smooth or not. Back about two years ago when I replaced the TPS, I checked the new one and it was good. But I did get the Oreilly brand part, BWD, which has screwed me over on something as small and cheap as a relay, so maybe I should double check it.

The TV cable is a little frayed, but it seems to be operating fine despite that. At WOT, it's as tight as I could get it. I probably should replace it before it eventually snaps, but it's not too bad, and I don't have anywhere to jack up the car right now. The shifts are great, they definitely do not go into gear early. Before I adjusted the TV cable, the 2-3 shift was OK, but the 1-2 shift was super early, like around 1500 RPM. It's much better now. I didn't drive it too long like that, so I don't think the tranny got damaged.

I will try to take a video to try to give you a feel of it. But the best way I can describe it is, it feels perfectly fine, it still pulls, except that it feels like you're giving it medium throttle and not WOT. Then when it gets to around 3.5-4K, then it finally feels like WOT and the RPMs go up fast. Which is funny because I thought these TBI engines performance peak at 3.5-4K RPM, not get better.

Also manually shifting the tranny does not change anything, it still does the same thing.

Also I have retightened the header bolts since the install, but not the y-pipe bolts, since I don't have anywhere to jack up the car. It does sound like there might be a slight exhaust leak. And I know exhaust leaks affect under-load performance, but I don't think just the y-pipe would affect it that much.

FreeSpirit

Quick update...

Advanced timing to 6*. I got shocked twice while doing it, so I sanded my chassis ground to bare metal again. (The part of the body where the battery is grounded to). It keeps rusting, how can I prevent this?

It definitely runs better, but I'm STILL having the problem. Sometimes at WOT it feels like I'm only halfway on the throttle. Even though it only happens under load, it doesn't seem to be dependent on how much load. (no difference whether I'm going up a hill or not.)

Checked the injectors while the air cleaner was off, the spray seems fine at idle and at throttle.

NCC-2569

iTrader: (1)

How did you get shocked twice, man?
That sounds like some defective spark plug cables to me, which could be part of the problem.

Night rider327

iTrader: (13)

Apply die-electric grease to the bare metal and cable ends. Die-electric grease is made for that type of stuff.

I do not think that is why you got shocked though. Sounds more like you got a bad spark plug or coil wire. Go crank engine up in the pitch dark and look for arcing plug wires (flashing light)

FreeSpirit

Well you guys were right, 3 of the spark plug wires had pretty bad melt/cracks in the insulation. There was certain parts of the wires near the bottom of the headers that were close on some of the back plug wires.

I had already checked for arcing and didn't see any, but it probably would have showed up under load.

I replaced all 8 wires for good measure, and made sure the wires don't get close to any part of the header. Also made sure the wires are tight and won't move around. Looked under the hood a few times after driving, they're still good. The car runs better now, but I'm STILL having the problem.

It's been about 2,000 miles since I installed the headers. Would that be enough to foul the spark plugs or plug the cat? I hope not, the cat is brand new, and I didn't check the plugs because they seem even harder to get to now with the headers instead of stock exhaust manifolds.

FreeSpirit

Well it was only running better because I forgot to plug my O2 sensor back in. I guess I'll go get an O2 sensor tomorrow, but what if it just runs better in open loop mode for another reason?