I think I messed it up, and I don't know what I did!!

Well, I got one hell of a problem to deal with now. I pulled my intakes off today so that I could clean the IMRC plates, EGR, etc... While I was in there, I decided to gasket match the upper to the 2 lowers. I used an air die grinder with various bits, and did a pretty good job I think... Now I have a new problem after I assemble it and drive it. After about 4000RPMs I have NO power at all. If I get on it from a stop it really moves, then at about 3000RPMs I hear a noticable sound in air suction from the front, then at 4000 RPM it just won't go any more. If I let off the gas and allow it to shift, it'll accelerate more until it hits that RPM, and shifts again. It tops at about 55-60. And it takes it almost 15 seconds to get there, with me babying the pedal. I also notice if in Park, if I floor it it won't even reach the rev limiter. It tops out at about 4700-5000RPM. I don't know where to even start with this doosy. Anyone PLEASE give me some suggestions... I got to thinking that maybe a plug is not firing?? I may throw in a set of plugs tommarow and see what that does. I pulled them out today and the gaps were 50-55, so I regapped at .044 and put them in. I am at a loss, any help, and I will bow down!

RE: I think I messed it up, and I don't know what I did

RE: I think I messed it up, and I don't know what I did

On 1st Gens, Vacuum holds the IMRCs closed. When the solenoid is engaged at 3250rmps, the vac pressure is released and the springs open the imrcs. Check everything, sounds like they are stuck closed.

RE: I think I messed it up, and I don't know what I did

RE: I think I messed it up, and I don't know what I did

I started the car, and looked at them. I then disconnected the solenoid and they both moved and the car's idle changed, then I reconnected it and they moved back again and the idle changed back.> BTW it idles perfect and theres NO CE lights or codes... I was thinking maybe tommarow I should try that "cylinder balance test" my code scanner has in it. Or maybe a fuel pressure test? I tried unhooking the regulator and driving, but no difference... There'd be no way my gasket match porting would cause this would there?? (I HOPE NOT)!!

RE: I think I messed it up, and I don't know what I did

RE: I think I messed it up, and I don't know what I did

I dont see anyway you could mess up the gasket matching enough to cause what you are seing.
I'm with Jeremi here.I would triple check to make sure they are operating correctly.

RE: I think I messed it up, and I don't know what I did

RE: I think I messed it up, and I don't know what I did

Ensure all of your electrical connectors are hooked up. Ensure nothing mechanical is binding. Are you absolutely sure all your gaskets stayed in place when you put it back together? When I ported mine the TB gasket moved and I had a big vacuum leak. Take your time and go over it with a fine toothed comb. A really good light helps as well. Good luck.

RE: I think I messed it up, and I don't know what I did

RE: I think I messed it up, and I don't know what I did

tell us exactly what you did how did you clean the egr and the etc. part ? I am not sure but isnt a gen 1 throttle body partially vacum actuated? you have good low end then severe bog? where did you grind-port match?

RE: I think I messed it up, and I don't know what I did

RE: I think I messed it up, and I don't know what I did

First I took off the rails and injectors. I then removed the throttle body. After that I found that the hole in the manifold that goes to the EGR was clogged so I unbolted the 2 bolts to the EGR and all the bolts that hold the upper/lower manifolds together and took them out. I used a vac. pump to check the EGR operation which was OK, and I sprayed TB cleaner into the EGR valve/tube, and cleaned the 2 lower manifolds (with the IMRCs) good. I then noticed on the upper where the runners connected to the 2 IMRCs that the gasket was much bigger than the ports, so I opened them up a bit more to match the gasket, and polished them up nicely. I then took a good 1/2 hour cleaning aluminum shavings out of the plenum, and bolted it all back in. I also cleaned in the heads where I could see the valve stems with a toothbrush and some TB cleaner. I did the key on/off about 10 times to prime the rails and she fired right up, so I took her out for a spin and noticed a MUCH louder air rushing sound comming from the air cleaner area. I also noticed a big difference when I hit 3000RPMs (IMRC opening I assume) And that I never experienced before like that!. The IMRCs were carboned shut, and took a LOT of cleaning to get moving freely.

After the poor first run, I first suspected the IMRC plates, so I looked at them and with the engine running, I can connect/disconnect vacuum and see the shaft move open/closed on both of them. I also pulled the spark plugs that have been in there almost 20K miles. They are 764s that I gapped to .044 when I put them in but they were all .054+, so I regapped them and no diff. Thing is that when in park, I can floor the gas and it won't even hit the rev limiter, which makes me think I am running on 7 or less cyls either by no spark or maybe an injector not working.

RE: I think I messed it up, and I don't know what I did

RE: I think I messed it up, and I don't know what I did

Come to think of it, I think when I was putting on a fuel rail or another piece I may have unpluged an injector wire, I wonder if that could cause that big of a problem. I'll have to check tommarow after work. Please keep comming with the ideas though!!

RE: I think I messed it up, and I don't know what I did

RE: I think I messed it up, and I don't know what I did

Nope, its all connected, and the IMRCs seem to be operating fine. You think the Cylinder Balance test thing that my code scanner has might help??

RE: I think I messed it up, and I don't know what I did

RE: I think I messed it up, and I don't know what I did

I dont know anything about the IMRC's, but from what you described(louder air/suction sound at idle from the airbox tube), it almost seems like the IMRC's are operating BACKWARDS. is this possible? From what I understand about how the vacuum solonoids operate, it sounds like they are OPEN below 3000RPMS, and are CLOSING once you reach the 3k mark. If it is possible for them to work backwards, then look into reversing them, however that might be.

I can dig into a Holley 750 all day long. You are describing acceleartor pump problems perfectly, or vacuum secondaries that aren;t operating properly. We were messing with throttle linkage on a twin 660 CFM Tunnel ram one day, and somehow we got the secondaries opening at low rpms, and closing at higher rpms, and it did exactly what you are describing. free reving up to 5100 rpms, but no PULL past 4000 when in gear.

Just a thought. Sorry if I am way off, but worth checking into.

RE: I think I messed it up, and I don't know what I did

RE: I think I messed it up, and I don't know what I did

did you index the crank closing valves when you cleaned the valves? then swabbing cleaning the deposits completely? what did you clean the valves with? o2 sensor safe ? can you see the egr diaphram move under throttle ?

RE: I think I messed it up, and I don't know what I did

RE: I think I messed it up, and I don't know what I did

I dont know anything about the IMRC's, but from what you described(louder air/suction sound at idle from the airbox tube), it almost seems like the IMRC's are operating BACKWARDS. is this possible? From what I understand about how the vacuum solonoids operate, it sounds like they are OPEN below 3000RPMS, and are CLOSING once you reach the 3k mark. If it is possible for them to work backwards, then look into reversing them, however that might be.

Click to expand...

Craig, the vacuum keeps them shut below 3k. This way you make more TQ at low RPMS.

One other thing though, when IMRCs open up past 3k, does the computer also send more fuel to the injectors ? More air, more fuel, right ? So Maybe you're pump is not up to game anymore, or FPR is stuck, or ... damn, I'm running out of ideas ...

RE: I FIXED IT!!

RE: I FIXED IT!!

Wow what a PITA!! Well, I had the G/F's dad drive it because he is an excelent shadetree. He said oh, no problem, its the cats. I was like WTF?? It runs great until I do the intake, and he says its the cats, which I haven't touched?? Well I pulled the exhaust and gutted all 3 cats, and VROOM, it runs like a bat out of hell... I never remember this much power even when it was new!!! I alread had cut the muffs off, so it has a NICE rumble to it!! Gotta get muffs though because of the drone! But shes all good now except a check engine light b/c of a bad EGR sensor.

THANKS ALOT GUYS!!!

RE: I FIXED IT!!

RE: I FIXED IT!!

That makes no sense whatsoever.The only thing I can possibly think of is whatever cleaner you used to clean the valves got into the cats and clogged them up.

WOW, I'm glad it runs good though.

RE: I FIXED IT!!

RE: I FIXED IT!!

I used seafoam and a toothbrush. And some TB cleaner spray. I do know that the cats were getting clogged before though, as it was having a slight problem above 4500RPM, but not just cutting out completely like this. This made me think a bad fuel pump or weak IGN.

RE: I FIXED IT!!

RE: I FIXED IT!!

hmmm you got me worried now..Seafoam? i just cleaned my trucks throttlebody intake and one bottle in tank with Seafoam due to great raves from friends about it. I too have idle and poor accelleration issues now. Im going to go for high flow cats and some new O2 sensors now for it.

1995 DK BLUE Lincoln Mark VIII
1998 DK BLUE Chevrolet 1500
1979 WHITE Trans AM
2004 BLACK HONDA CBR 600RR

RE: I FIXED IT!!

RE: I FIXED IT!!

I agree Chris. Jeremi, makes sense... thanks.

However, when I had to throw an intake on my 4.6 SOHC last year, it took a few miles(about 20 minutes of run time) for the "re-learn" to kick in. The car had no power, no throttle response, and it idled like silk. I was a bit worried something was wrong, like a cracked runner or something(phenalic intake).

Turns out, after reading a few TSB's that it just takes some time to re-learn with my battery disconnected for 2 days, and just about every sensor under the hood unpluged.

When it 're-learned" it ran better than ever. Do you think Wackyz' problem was really the cats? or just a timely coincidence? Either way, its fixed. Nice job.

On another "gutting cats" note, an california owners gut their cats, and still pass the sniffy test?

RE: I FIXED IT!!

RE: I FIXED IT!!

I would guarantee I'd fail an emissions test b/c of the stink of the exhaust, smells fuely!! I did drive the beast 2 days (probably 50+ miles) and it just got worse and worse. Sierra, I didn't put the seafoam in the tank, I used it in the heads where the valve stems are. Ya I know, real dumb idea. When I tried to start the car it wouldn't turn over, and I thought how in the hell did I sieze the motor by messing with the intake. Turns out there was so much ##### in the cyls that it couldn't compress it. I had to pull the plugs and crank it over.

RE: I FIXED IT!!

RE: I FIXED IT!!

AAAHHHaaaa. I might be on to something here.

RE: I FIXED IT!!

RE: I FIXED IT!!

Yeah, and I probably f-ed my O2s up, because of the god-awful smell comming from the exhaust. Cars, what a wonderful invention!