turnin20s

I set my valves today with the motor running. Backed them off until they started clicking, then turned till they stopped and added 1/8 turn of preload. So my valves are now set. I let the car cool down a little bit then checked the oil and made sure everything was tight. Then I took it out and right away it had tons more power, but after it got warm (about 170* on the guage) it started to run like garbage, missing and not wanting to idle when in gear and then the check engine light would come on when it would idle down low. When the car is warm and in gear it tries to idle at ~500, but when I let it idle in park or neutral it idles ~1000. And also when I was driving it if I hold the rpms ~2500 it misses really bad, but I can't really tell if its missing over 3000 rpms, but the car shakes like it has a miss. I talked to a few guys around here and they said that it wants to run good in closed loop, but when it warms up it goes into open loop and starts to run like crap.

My cable should be here today so I can hook up my laptop and see what its doing and whats not working, but the mail won't be here for at least 3 hours. Should I just wait and see what the scan tool says or what are some things to look at right now?

I reused my opti and most of the sensors that were on the motor and they were in working order before the motor was rebuilt. And the headers were used so the coating shouldn't have messed up my 02 sensors.

Anything that I may be overlooking? I changed the plugs a couple days ago and everything is on all the way and the wires are right, but if you have any idea what else it could be?

Thanks in advance

93BlackTA

I'm having the same trouble, i am going to check my wires/plugs and valvelash again this weekend....i'll be following this thread to see if you get it figured out..please reply with info if you find something.and i'll do the same...thanks

turnin20s

Well my cable showed up after I left for work of corse, but hopefully tomorrow I'll run a scan and see what I come up with.

On another note I talked to a local guy and he said that it may be the temp sensor. Any thoughts on that?

turnin20s

Anyone? The laptop I was going to borrow forgot to show up today so I have to wait until tomorrow, but I could use some help. Car runs good cold, but once its warm it misses

turnin20s

Ok, I adjusted the valves again and put a new temp sensor on the water pump and its still running like crap. I got the laptop and have the Datamaster software installed on it and the cable ready to go, but the instructions on how to use it are really long, about 60 or so pages and me and my brother have been reading them but haven't hooked it up yet. But the miss keeps coming back, mostly below 3000 RPMs when its warm and when cruising my RPMs are at 2500 and it misses there. I really can't figure this out and have done everything that I can do so far. I honestly think my car went better in stock form than it does right now with all the mods in my sig.

I'm going to read through the instructions for the datamaster some more, but I think I may have a vacum leak or my mass air is bad or any of the other sensors, or my pushrods are too long, or my injectors are too big, or ?????????????????

I'm really stumped here but hopefully the datamaster will help me out or in anyone has any ideas please let me know. My plug wires are on right and all the way clipped on and not burnt.

I just thought that this motor would have loads of torque and its just a dog.

If I run the Datamaster I'll post up what I figure out and hopefully I'll do that before too long today

Sorry for all of the rambling

turnin20s

One more thing, I'm on my second set of plugs gapped to .050 stock heat range. Should I change them out again and gap them to something else? What plugs are recomended? NGK TR55s seems to be the main choice but let me know.

I'm also going to get a fuel pressure regulator and see what thats sitting at.

*EDIT* And all of my EGR stuff is deleted and blocked off.

I'm going to hook up the laptop in about 20 minutes and will post up what I find if anything.

turnin20s

Ok update, I ran the datamaster and have a DTC 33: map high

My brother is bring me a new MAP sensor, or could it be something more simple?

Other than that I think that my injectors may be too big, but I need to do some WOT runs and see, but at 1875 RPMs they are only at a 4.1 DC and my fuel trim cell is at 18 at the same RPMs

Also my spark advance is at 42* at 1875 RPMs and about 29* at idle 900 RPMs.

My MAP KPa is at 40.6 at 2000 RPMs, but should I trust those #s since I have a MAP trouble code?

If you neede any more info let me know and I'll post it up. I'm hoping that the MAP sensor will fix my problems, but I'm not counting on it.

blue

I would rule out anything mechanical. It doesn't sound like ignition either if it runs fine until it gets hot. Have you checked for vacuum leaks? I had a significant leak on my intake elbow where it seals over the throttle body and it idled fine for about 10 minutes, then it started idling really bad. I had forgotten to tighten up the clamp; once I tightened it the car was fine. If air is getting into the engine that the computer doesn't know about (that doesn't go through the MAF) it will run badly.
If it's a vacuum leak and you can look at the air fuel ratio it should be on the lean side. I was told that the effects of a vacuum leak will also be more noticeable after the car warms up because factory tunes typically make the car run a little rich until it's up to temperature.

blue

I don't know how much you know, but just in case, lean would be something above 14.7.

turnin20s

Thanks for the reply, hopefully I'll figure something out here soon. My brother just changed the MAP and is working on the fuel filter and then we are going to make some runs and clear the trouble codes and see what happens

Ricardo

what is your MAP reading at Idle?
I run a GMPP 847 cam in my 383 and it Idles at 50 KPA in neutral 55 KPA in gear.

turnin20s

Ideling in neutral its about 40-45 KPA and in gear its about 45-50 KPA

Then at WOT @ 6350 RPMs the MAP is reading 92.6 KPA

Ricardo

Your map readings seem right.
I had to run an open loop tune to get rid of all bucking surging problems under 2300 RPM.
No way around it if you are running a 306 cam.
You can probably make it better with lots of changes in the tune, but will never get rid of the surging and bucking completely.
Dont know if emission controls are very strict where you live.

RG

turnin20s

I don't have any emmisions anymore, well except for the carbon canister. No cats, EGR, or AIR pump on my car anymore.

The only thing is that its not really bucking, but more of a missing like it may be fuel related. I'm also thinking that my pushrods are too long, but that will be taken car of here shortly. But I have talked to a few guys and they said the only way to really figure out whats wrong is to put it on the Dyno and get a good tune done. But the only problem with that is its going to cost me $300-$500 to get a dyno tune and I really can't afford that right now, but I'll make it happen if I have to.

Also on my graph for the DataMaster the 1st gear pull looks nice and smooth, but the 2nd gear pull is really shakey. I don't know what that means, but my car doesn't run like it should, IMO I think it went just as good or mabye better in stock form.

And I read that the DataMaster can't detect a miss fire on an OBD1 car, is that correct? I may get another set of plugs and gap them smaller, but if someone could suggest a plug for me I'd appreciate it. I'm just running stock heat range plugs right now at .050 gap

Ok I'm going back to try to get this graph loaded on my desktop

turnin20s

Alright a little update, I'm going to order a new opti wiring harness and MAP sensor wiring kit to see if that helps, I have been researching and these pop up every now and then with similar symtoms to what I'm having. The clip on my MAP sensor wiring is broken so that needs to be replaced for sure and I'm going to test the Opti wiring to make sure, but I thought I'd rather be safe than sorry and overlooking something simple.

I also am going to recheck the pushrod length because I think they may be too long but I'm not sure if that would cause my problems but it might be another contributing factor

Thats all I have right now, but I'll update as I figure more stuff out