About 4 years ago I replaced my stock manifold with an Accel unit. I also purchased and installed a brand new EGR. It's a vacuum EGR so it's not like I could FUBAR the install and I know the previous EGR was working great with the same vacuum line.

After the install my EGR diagnostic code started to fly out all the time. I just went into my chip and disabled the check by changing it from 30mph up to 255mph.

Well my car failed smog last weekend and one of the issues was that my NO was 1700ppm, the max allowed is 700ppm!!! 1K over the allowed max. Keep in mind it HAS passed before since doing the manifold and EGR, could have been luck though.

I can't help but wonder if my EGR is even working.

Are there any known issues with the Accel manifolds and the stock EGR's? The EGR port on the top of the manifold looked just fine but maybe the manifold doesn't line up correctly with the EGR port on the stock heads? I forgot to check that 4 years ago.

Thanks!

Alex

 

When you installed the new intake manifold gaskets did you punch out the hole for the exhaust gas passage in the gasket?

I know of no problem with any TPI intake manifold and EGR.

 

I used a set of Felpro and IIRC it already had the passage accounted for in the gasket.

If I'm wrong then I will kick my own ***.

I'll have to go through my receipts, get a part # and check.

Thanks for the lead!

 

I replaced my EGR and solenoid with brand new GM units when I did the Accel manifold install and right after the install I got an EGR diagnostic code but just got rid of the check in my chip. I pulled my plenum over this last weekend and tested my EGR and all vacuum lines and passages. I even hooked up a manual vacuum (my mouth on the end of a hose) straight to the EGR and reassembled the intake and started the car to see if the idle changed once the engine was warmed and I sucked. Nope, the EGR works perfectly as it should but the idle doesn't change and my smog cert readings verify this.

Ok, I have some more questions about this...

I have my entire intake stripped down to just the distributor and manifold now.

When I removed the plenum, I blew through the EGR passage on the passenger side to be sure that it was flowing freely. It was and I could easily hear the air coming through right at the throttle body on the inside of the plenum. I also noticed this passage had allot of carbon, by no means clogged, not by a long shot, but it looked like the EGR had been working you know.

After removing the SLP runners I blew through the EGR passage on the passenger side runner and made sure everything was not blocked by gasket or anything. Check, worked great. So I know air can go through the runner and into the front of the plenum. The EGR passage on the runner had the exact same carbon build up at the plenum passage.

Then I checked the manifold. I can shine a light clear through the EGR passage from where the runner meets all the way to where the EGR goes. I of course removed the EGR at this point. I also noted the exact same carbon build up in this passage so everything is so far consistant from the front of the plenum all the way to the EGR. So far good news yet a little confused on the carbon build up if my EGR was supposedly not working.

Now before I remove my distributor and rip my Accel intake off, WHERE exactly do the exhaust gases route from and to BEFORE the EGR? I presume there is a passage in heads that match passages in the Accel manifold that go to the EGR, then when the EGR opens, the gases are passed by the EGR and dump in the front of the plenum behind the throttle body.

Is that all correct? I'm still confused though on how exhaust gas gets into the heads to go through a passage and into the intake if the exhaust goes out the exhaust valves into my headers, lol.

I know I have AIR tubes on my headers but those go into a black plastic box and dumps into my throttle body and routes to my catalytic converter right?

I notice that in my intake in the passage that I think should go from the heads to the EGR that there is a VERY light coating of a VERY dry black powder, like hardly anything but enough to get my finger dirty, totally different from the thick wet harded carbon that after the EGR going to the throttle body.

Can someone please explain how all this works so I can be sure I have it right. I have a brand new set of stock replacement FELPRO manifold gaskets that have the hole for the passage from both heads into the intake ready to go on but I just want to be sure in my head how it all works you know.

Thank you VERY much in advance!

Alex

 

Yes, the exhaust gas goes from the port in the head to the passage in the intake manifold under the EGR valve. When the EGR valve opens, the gas goes up tube on the passenger-side runners and under the plenum into the space behind the throttle body.

The AIR system takes regular air from the engine compartment, pushes it thru the pump, and to the black plastic box. That box has two valves that control whether the air goes to the catalytic converter, or to the tubes on the exhaust manifolds.

The bigger port on the throttle body is for the PCV system. That comes from the valve cover. The other smaller port on the throttle body goes to the charcoal cannister.

 

How does exhaust get from the combustion chamber into that passage in the heads that goes to the intake?

 

There's a hole in one of the exhaust ports of the heads.

 

Gotcha!

Thank you for all the help!

 

Deleted response.

 

Ok, lol. HELP!

I pulled my manifold and the gaskets were correct, the EGR ports in the heads are unblocked and match the EGR casting in the passenger side of the Accel manifold perfectly. I took a few pics to help you help me, lol. Please excuse the filth, I haven't had it apart in over 100,000 miles.

The Accel manifold has no passage for the EGR port on the drivers side head, only the EGR port from the passenger head.

Here is a pic with the manifold off showing the EGR passages:



Top of the Accel manifold showing where the EGR passages meet:



This pic shows how the Accel manifold matches up the drivers side head EGR port however the manifold does not have a passage. It only has a small indent.



Here is the passenger side EGR passage in the manifold, the one that is real, lol.



Here is the bottom of the manifold with the tray removed so you can see the passage:



This is a view looking at the passenger side of the manifold showing how *I think* it works.






So, WTF, lol. My EGR is brand new and I can hook a hose up to it, suck and the diafram moves perfectly and it holds untill I let the vacuum escape just as it should. So why if my passages are not blocked did the idle not change when I manually applied vacuum to the EGR? I am SO confused! Even when the EGR off and vacuum applied, I can blow in 1 port of the EGR and it flows out the other just fine too! ARGH!

Thanks!

EDIT: I just remembered that my TB is a 52mm unit from TPiS. Even though I can blow into the EGR gas passage on the side of the plenum and hear air clearly coming up into the plenum right behind the TB MAYBE the gaskets TPiS gave me with it aren't allowing ENOUGH flow? I mean I am only having the pressure from 1 heads EGR passage right?

Also I noticed that the EGR passage in my SLP runner just doesn't seem to flow like it should when I blow. I've cleaned it and it helped but not much. Maybe since all of these parts were new and had 0 carbon build up (except the stock plenum) that maybe the SLP casting needs work? Again due to only having pressure from 1 heads EGR passage?

I'm kinda grasping at straws here...

 

I just replaced the EGR valve on mine a week ago with the correct valve for a '90 (old one was an '89 from the donor 350 car) and got a code 32 again. Everything checked out just as yours did. When my car was TBI it had code 32 as well, seems like once 32 pops up in the ECM you just can't get rid of it.

 

Alex, hi

I have the same year car as you and i also have the acell lower intake and right after the install the code 32 EGR keeps popping up, tho it only comes on when my car is cold and i start to drive ( start and roll ) the only other time is traveling at a certian speed, ex mine will come on if i travel at 110 km\hr and only at 110 not 100 or 115. Funny thing tho it comes on only for a short time maybe a 5- 10 min interval at a time then it goes out. I just ignore it , i have gotton real tired of hooking up my scanner just to see my old friend #32, hope it works out for ya

 

Hmmm, well I have the same Accel manifold and the factory original 20 year old EGR in my car. I got 117 and 145 NOx numbers. And that was with the plug on the passenger side valve cover unplugged by accident. (It's hidden underneath the AIR tube). Would probably do a bit better with it plugged in.

I was going to say check to make sure the tiny hose that plugs in underneath the TB is plugged in and allowing air to go through, but you've said that it's blowing air into the TB fine.

You did get the proper negative pressure EGR valve and not just a standard one right?

 

I've got the EGR that dealership sold me, I can make it work with a little vacuum so I presume it's correct.

I'm allowed 700ppm on my NOx but I scored 1400ppm. Before chasing this EGR ghost I did a complete, and I mean a complete tune-up. Brought my NOx down from 1750ppm to 1380ppm. That's why I'm convinced I'm still failing due to my EGR since I had code 32 as soon as I installed the manifold.

It's starting to sound like I need to buy a stock manifold just to pass smog because the Accel does not pass ENOUGH exhaust gas since it only uses 1 head

 

I'm wondering if the TPIS Big Mouth is made the same way. I'm also curious if the passage in question is actually in the manifold and just blocked off or completely missing. If it was just blocked off you could just open it up.

 

Are you referring to the passage that meets the drivers side head EGR passage? It's not even there in the manifold to be blocked off. It's just not even cast into the manifold at all.

I've got every part and passage cleaned as much as I can I know this improved flow under the plenum and through the SLP runner as those were clogged the worst. I'm putting to back together tonight and crossing my fingers. I even removed the TB and checked all of those passages.

All looks good, as before though. I'm honestly not expecting any of this work to pay off

 

The factory manifold is the same way. It only takes exhaust gas from the passenger side head. The reason its on the drivers head, is that they fit on either side of the motor. Have you replaced the EGR solenoid? Get to Autozone, and rent a vaccum pump...I don't think you can pull 18-20in/hg. The ECM checks for a drop in vaccum when the EGR is commanded, I be 100% sure you don't have a leak somewhere. Good luck chasing this problem down.

 

Well I got everything cleaned and reassembled yesterday and got some test drive miles on it yesterday afternoon including some good highway miles with cruise trying to get code 32 to set off after re-enabling the check in my chip.

The most difficult thing was cleaning the passage under the plenum, what a bitch. Muct have taken 2-3 cans of brake cleaner alone. The passage in the SLP runner took some time too.

Good news is that after a couple hours of highway driving with the cruise I got no code 32, YET, lol.

I do have a small vacuum leak I'll be fixing tonight. I also replaced a few vacuum & PCV hoses while I was in there.

I'm going to smog it again this weekend and hopefully I pass this time, lol! I'll be driving to to work everyday this week and tweaking things.

 

Any luck?

Its possible you got a bad manifold that wasnt completely machined with a hole for the EGR passage. By the way, there is only one passage on the passenger side.

 

I've still been driving it everyday to work and doing some final tuning with my notebook last nite. STILL no EGR code!

The manifold seemed fine. I think it was a combination of the passage under the plenum and the plenum/runner gasket on the EGR side getting pushed down a bit when I slid the plenum in and that cut off a bit of the flow too.

I have a smog appointment Saturday so I'll have real numbers then.

 

have you check what duty cycle your egr is operating at for 15mph and 25 mph? when mine failed emmisions, i check the duty cycle and it was only operating at 50%. i change the bin to make it at 100% by load vs. rpm. after doing that and setting my max advance to 20 degrees, it dropped the nox from 700's to 200's. but my engine is extensively modified, and made my map vs. egr duty cycle set at different points. stock setting is 50% @ 70kpa 1200rpm. and with your intake and i think you said bigger throttle body, it might actually be sitting at that point instead of at a 100% duty cycle.

 

Hmm, that's a good thought. Increase the duty % to compensate for more air flow.

Here is what my stock table is set to, what changes would you suggest?

BTW, here are my smog readings from when I first smogged the car after a year of sitting before doing any kind of a tune-up and stuff like I have to give you an idea of the RPMs..

HC - 15mph/1548rpm: 130ppm (Max allowed is 108ppm)
NO - 15mph/1548rpm: 1766ppm (Max allowed is 767ppm)
NO - 25mph/2011rpm: 1058ppm (Max allowed is 706ppm)

 

well i wouldn't want to suggest what to do unless i see some logs of what kpa vs. rpm you are sitting at while cruising. but more than likely that 70kpa vs. 1200 rpm shouldn't be at 0. are you using AJUP? stock setting for AJUP is 50. but since your car is a 305, i don't know what bin it uses.

 

My stock bin is AXXF and that is a table from the stock unmolested bin.

Also I run about 50kpa at the test RPM and load.

 

well if you're at 50kpa while at that rpm, you should be at 100% duty cycle. do you have egr logs to confirm this? just cause its supposed to be there, doesn't mean it actually is. if you confirm it, then that eliminates everything except the mechanical part of the egr. but it could also be something totally different. can't hurt to eliminate causes though.