intake gaskets?

[dakota]

So, I met a really nice guy in town who has a iroc r/t. He let me swap every thing that we could unplug to my spirit r/t to try to make in run smooth and nothing helped. It still has a miss and surges when cold and gets better when it warms up, But never goes away. Has any one ever had intake gasket trouble? Leaking between runners? Sorry if it sounds like I'm grasping for straws because I am! Jeremy

[xtrempickup]

have you pulled codes on your car? i doubt its a gasket leak, sounds like a HG leak

[dakota]

It throws no codes, and does not have creamy oil, bubbleing in the radiator or any coolent loss. I have also had the fuel system cleaned.

[xtrempickup]

you could buy and replace the gaskets, they arent expensive. try replacing the plugs and wires? see what they look like>

[rx2mazda]

Sounds like your fuel injector wiring harness, did you swap to his? I had the same issue but I was able to figure it out within minutes. Moving the harness smoothed the engine out. I had to take apart the harness, clean it, close the connections a little and I used some dielectric grease. Check this if you haven't yet. Good Luck!

[dakota]

The motor has new plugs and wires. I have new intake gaskets. Is there any thing to look out for when installing them? Jeremy

[turbo1168]

Before spending any more money on parts, I would do a compression check on the cylinders, and also scope the ignition system. A compression check will tell if you have a burned valve, weak ring sealing or a blown head gasket between 2 cylinders. IT IS possible to have a blown head gasket without coolant or oil loss, look at a picture of the top of the block and you will see this. A scope will be able to determine that the cylinders are getting good spark to each plug without a misfire. Your car has a distributorless ignition system with multiple coils( I believe, it may have 1 coil pack). It is possible to have a bad coil that still allows the car to run. ALSO, verify the timing belt is properly aligned with each cam and the crank.

A scanner at a mechanics shop can also "view" the individual sensors to verify they have the correct readings. A vacuum leak can also cause a miss. Some shops have a smoke machine to check for vacuum leaks. Good luck!

[dakota]

3 driffent shops have had this thing on the scanner. I have done a leak down and comp test. And I put the timing belt on my self. I do have factory service books.

[turbo1168]

OK, that answers half my questions. What about a scope, did they check the waveforms for the ignition? The coils can be tested with a meter as well, across the primary windings and the secondary. Fuel flow at the injectors can be checked with a pulsing flow tester. It uses a device that pulses each injector individually, while monitoring a fuel pressure gauge, to see how much the pressure drops for a predetermined number of pulses. Speaking of fuel pressure, is it in spec.?

As far as a scanner goes, it is only as good as the person watching the screen. Just checking codes doesn't give you a great deal of information on a pre-OBDII car. It can have a sensor out of spec, without setting off a code. As long as the sensor is within a certain tolerance, the ECM thinks all is well. If you can hook it up again, look at the map sensor, coolant temp, O2 sensor, etc. readings

Few more tips (or questions), how do the plugs look? All 4 evenly colored? If you have 3 tan plugs and 1 that is white, that would indicate a lean condition. What kind of vacuum is the engine pulling? When did this condition start, was there any changes to the car performed prior to this? And have you checked that all vacuum connections are correctly located and tight?

[dakota]

Yes it has been on a scope twice. I watched the injector pulse and the hole 9 yards. We checked the fuel pressure with a remote gauge while driving. I have repalced the coil, injectors, tps, o2. checked the map, computer. The last time I checked the plugs they looked tan but, I will check again in the morn. As far as when this started it was like that when I got it 8 yrs ago. It's a cool car but I must admit I'm about done with it. It never fouls plugs or smokes but it does stink from the exhaust. I have put a new cat on as well. Thanks Jeremy

[turbo1168]

Well good luck with that. if I think of anything else, I will let you know. Hard to diagnose a strange problem 3000 miles away!