Stock car + cobra intake = total loss of low end ??

[jb89coupe]

Hmm...well if he is having a lean problem I think it is injector related (because the injectors are directly related to the process of an intake swap and not the fuel pump)...not because of the 19's not being enough (they are)...but because he broke a connector maybe or his injectors are not installed correctly...

Check for fuel leaks (did he replace the O-rings or have all the O-rings) when installing the injectors back in...

As some of the others have alluded to...it could be a vacuum leak/timing issue...that was the first thing I thought of before I read the other post...

Probably the "top end" gain you felt really isn't there but it feels like it is because of the "total" loss of low-end...so something semi-serious could be the problem...

Your friends car doesn't need those 24's as you said...

A Cobra intake is fine on stock engine...and those other two bolt-ons are fine also...

Oh and check all connections (compare it with your car if you have to...)...it isn't likely the fuel pump messed up between that time of the intake install...

Good Luck with your friends car

After the install there was a vac leak at one of the injectors. We changed the o ring and reinstalled that fuel rail, no more leak. I drove this car the other day and it really feels like it's going to blow up at 4000rpm+, vibrating and knocking like crazy so it's definately not good. There's no fuel leaks, no vac leak that we can find. I've been over all the connections myself more than once. Timing is at 10* right now, but we've played with it 6-16. He helps me with my car all the time so I feel like I should return the favor but I'm running out of ideas. Could a vac leak/bad injector really make an engine shake like that?

 

[Blandnuts]

I would check over the injector wiring, seems like there's a mix up. Check what you guys worked on before looking at other places. Good luck.



Fred

 

[5spd GT]

Yeah to go along with blandnuts idea...check to see if the correct injector harness was plugged into the correct injector...I know my harness (if you just laid it over the lower intake) was pretty self-explanatory when connecting them...they all almost connected themselves on the way they laid out...if that made sense?

I'm confused on the vibration thing...their is obvoiusly some sort of balance/misfiring issue going on...?

Double check those connections...whether they matter or not...like the pcv valve/plugs/EGR/vac lines/etc...

Good Luck man...that can't be fun trouble"shooting" it when their is no target

 

[FastGT94]

My brother just put a cobra intake on his 91 vert. Car is stock except for the intake w/ 3/8" spacer, 65mm ford racing tb, and 70mm c&l ma tube. After he put the intake on the car totally lost its low end. You can't spin the tires in first gear in this car unless you rev it to 4k and dump the clutch. It feels like it pulls farther up the rpm range but there's *no* low end power anymore. I know when I put my performer on I didn't notice much if any loss down low. Is this normal with the cobra intake?

Ok, You made sure to put a gasket on each side of the intake spacer right?

Did you reinstall all the stock electronics on the new TB? All new gaskets too? Did you verify the TPS voltage? (Essential on pre 1994 cars).

Is the 70mm C&L made for 19# injectors or 24# injectors? That can cause issues too. If its running lean after swapping only the TB, MAF and Intake, I'd look to vaccum leaks or fuel issues. Be sure the injectors are hooked up in the right order and there are absolutely NO vaccum leaks.

You don't need 24# injectors with the stock heads and cam so don't bother with that.

The only thing that could have gone wrong is something with improper seal on the gaskets or injectors, a connector hooked up wrong or the wrong size sample tube on that C&L.

-Verify no vaccum leaks (All ports under the intake plugged up?) All injectors seated properly? No cracks in the intake?
-Double and tripple check all electrical connections.
-Double check spark plug wire routing
-If all is well, swap out the C&L with the stock MAF and see if that clears anything up.
-Then try swapping back the stock Throttle Body

Oh, and everytime you make a change to that car, no matter how small it is essential to reset the computer by unhooking the battery for at least 20 minutes and letting the computer "re-learn" its new parts and settings. This can also be causing you some issues. Maybe even try this first, after clearing out all the error codes.

Remember, only do one thing at a time when hunting down the problem, or else you'll just keep adding more varibles to the equation. Good luck!

 

[tunedin302]

Ok, You made sure to put a gasket on each side of the intake spacer right?

Did you reinstall all the stock electronics on the new TB? All new gaskets too? Did you verify the TPS voltage? (Essential on pre 1994 cars).

Is the 70mm C&L made for 19# injectors or 24# injectors? That can cause issues too. If its running lean after swapping only the TB, MAF and Intake, I'd look to vaccum leaks or fuel issues. Be sure the injectors are hooked up in the right order and there are absolutely NO vaccum leaks.

You don't need 24# injectors with the stock heads and cam so don't bother with that.

The only thing that could have gone wrong is something with improper seal on the gaskets or injectors, a connector hooked up wrong or the wrong size sample tube on that C&L.

-Verify no vaccum leaks (All ports under the intake plugged up?) All injectors seated properly? No cracks in the intake?
-Double and tripple check all electrical connections.
-Double check spark plug wire routing
-If all is well, swap out the C&L with the stock MAF and see if that clears anything up.
-Then try swapping back the stock Throttle Body

Oh, and everytime you make a change to that car, no matter how small it is essential to reset the computer by unhooking the battery for at least 20 minutes and letting the computer "re-learn" its new parts and settings. This can also be causing you some issues. Maybe even try this first, after clearing out all the error codes.

Remember, only do one thing at a time when hunting down the problem, or else you'll just keep adding more varibles to the equation. Good luck!

Good advice .... prior to doing this, make sure the distributor is on the correct tooth. Bring #1 up to TDC and make sure the pointer on the balancer is on TDC and then see where the rotor is positioned within the distributor. If it is off by 1 tooth then it can make a big difference.

 

[jb89coupe]

...

Remember, only do one thing at a time when hunting down the problem, or else you'll just keep adding more varibles to the equation. Good luck!

Thanks for the ideas. I wasn't actually there for the install but I've looked over it a few times. Yes there are gaskets on either side of the spacer, the tps is set and the iab/egr are the original parts. I'm not sure if he reused the gaskets for those, I'll ask. I'll go over the connections again too. The computer has been reset numerous times since the install. Also I'm pretty sure his c&l came from a car w/ 24# injectors, but he had that on there before the intake with no problems (he had the tb on too, for that matter). I'll tell him to swap his stock mass air tube back to check.

 

[jb89coupe]

Good advice .... prior to doing this, make sure the distributor is on the correct tooth. Bring #1 up to TDC and make sure the pointer on the balancer is on TDC and then see where the rotor is positioned within the distributor. If it is off by 1 tooth then it can make a big difference.

I suggested that to him, but he said he didn't even remove the distributer for the install, just popped the cap off.

 

[Scott_B]

to change the lower intake you would have to pull the dist...its just in the way to leave it there.

 

[xplo89gt]

Yea, I remember definately taking my distributer out. But if he says he didnt touch the distributer, that rules out timing if he had no problems before intake install. Just to be sure check the timing again. Make sure you are setting with the spout connector out.

If he has 19# injectors, he needs to use the C&L 19lb tube. Also try the stock MAF to make sure. There has been many a case where C&L have caused many problems.

Make sure all sensors got plugged back in.
Did all the hoses get connected to the upper intake?

So he removed the distributer cap, was there any chance he took the wires off of the cap as well? or off of the spark plugs since wires can get in the way?
If so there is a good possibility of him swapping a wire and that would definately cause these problems.

Oh and by the way dont drive the car while its in this shape.
Good luck.

 

[cevtv]

to change the lower intake you would have to pull the dist...its just in the way to leave it there.

You don't have to pull it - but it sure is a hell of a lot easier......

 

[CManT1914]

You don't have to pull it - but it sure is a hell of a lot easier......

Yea pulling the whole distributor is not neccesary, but it sure is helpful.

 

[5spd GT]

If you don't figure out the problems with the little ideas in this thread...what I would do is do the intake install with him...get a new set of gaskets/align the holes properly/have everything plugged or plugged up where they go...

 

[grrrrrrr]

Sounds like you have a vacuum leak somewhere, possibly with the egr valve? Make sure it's bolted down good. If you have an unmetered air leak and your computer picks it up from a lean condition in the upper RPM band it will pull timing I think. This will cause the bucking and vibration you experienced at higher RPM's. I'll bet if you do your timing to a base of 13 or 14* and leave the spout out it will drive fine. You will still have a vacuum leak though and prolly a lean condition (not good). Definately search for a vacuum leak somewhere. Does it idle a little high? If you leave it idling for a while do the rpms drop about 100 rpm's after a minute when it's warmed up? It should do that, if not you have a vacuum leak somewhere.

 

[FastGT94]

If the timing has been verified, then the distributor is fine. The tooth off thing is just another way of saying to double check the timing.

If he didn't remove the distributor during the install, it may have made it more difficult to line up the intake and gaskets w/o shifting a gasket.

24# MAF and 19# injectors is a recipe for a poor running car, I'd start there if it is indeed a 24# MAF.

If he hasn't painted anything on the engine, you can spray carb cleaner around the intake and gasket areas. if there's a vaccum leak, the engine will suck in the carb cleaner and the RPM's will rise. The hoses under the upper intake are an often overlooked area. Or just hook up a vaccum gauge and see what it reads at idle. I belive around 14-15 lbs at idle (steady reading) is about right.

 

[FastGT94]

If you don't figure out the problems with the little ideas in this thread...what I would do is do the intake install with him...get a new set of gaskets/align the holes properly/have everything plugged or plugged up where they go...

Also a good idea, it seems like a pain but its worth a day or two of wrenchin to have a drivable car.

 

[SilverFox90]

i have basically the same things he has except headers and gears and i have plenty of low end.....light em up all the time so i def dont think its the intake like others have said it is prolly somethin wrong with the install