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No EGR = no idle?

Element

Element

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Pulled the EGR valve off the truck the other night and put a block-off plate on. The EGR valve was FUBAR, guts all rusted up and coated in mud. Started the truck up tonight for the first time in a while (had been waiting for a factory part to come in), and it started and idled fine for the first few minutes. Went in the house to let it warm up a bit, and come outside and it's sitting right about 300rpm, idling, and surging up and down maybe 100rpm. It sounds like there could be a very small vacuum leak, but when I pop the hood to listen for it, it sounds like it's coming out of the throat of the TB. Already replaced the gasket the TB "neck" plastic ring piece sits on, so I'm not sure what else could be leaking in there.

I seriously doubt pulling the EGR system off would cause it to idle so badly (especially when it idled fine to start with), but I'm not sure what else it could be. I've had recurring idle problems with the truck, and I've replaced the coolant temp sensor and the IAC valve, so the only things left (I assume) would be the TPS (wouldn't make sense that it'd idle fine at start but drop so badly as soon as it warmed up if that was the case), or possibly the EGR valve.

Not quite sure why in the hell this thing doesn't want to run right, but I'm starting to get pissed at the damn thing. It's an '87 TBI, and as little experience as I have with carb engines, I'm starting to wish this thing had a Holley or an Edelbrock sitting on top.

Anyway, new parts list - plugs, wires, cap, rotor, coolant temp sensor, IAC valve, battery, battery cable terminals, alternator, fuel filter, air filter.
 
Check engine light is out in the dash, and I don't have a scanner, so I can't pull codes.
 
You will definately have a code for no EGR. EGR helps to keep combustion temps down and help to keep it from pinging. Why did you remove the EGR in the first place?
 
Having a code really doesn't bother me, but if having the EGR off is going to screw the idle (I really don't see why it would, however), I'll have to pick a new one up. I was trying to figure out earlier idle issues (truck stumbled and occasionally just shut off when hot), and since I can't pull codes, wanted to try to eliminate whether the EGR was an issue or not, and dropping $50 on something that might not do anything seemed pointless. For all the goddamned new parts I've put on this truck, I could have bought a scanner...should have done that in the first place :doah:
 
I would say it's time to do two things. First would be to find an autozone or whatever and have them stick a tester on your truck. They will do it for free, and the codes will tell you what the computer sees. Second would be replace the check engine light and get a shop manual. The light was burnt out for a reason, and it may well have been the cause of your earlier idle issue (IAC? TPS?).
 
well, if you turn a paperclip into a U shape, and hook it into the 2 ports on the top row, right side of the ALDL connector, the check engine light will flash the codes stored. Itll flash 12 3 times, then any stored codes, and when its done itll flash 12 3 more times

Of course lookin at the above posts, if by out you mean its burnt out the above wont work. But if you mean its out, as in it aint lit, give this a try
 
A scanner and volt meter are your friend in this case as well as a manual of some sort that gives you voltage values and other info.
 
Light is burnt out, and right now, the only thing I want to do is set the Blazer on fire, I'm so tired of working on it. I'll get a scanner as soon as the budget allows, which will hopefully be before the end of the month. Also going to either get a "high flow" replacement cat (they're cheap on ebay), or just gut the stock cat. I have a feeling that's part of the issue on the hot idle problems - stock cat from 1987 with 90,000 miles on it is probably a bit clogged up.
 
Element said:
stock cat from 1987 with 90,000 miles on it is probably a bit clogged up.
Click to expand...


i dunno about that, mine is running at 252k miles, and still has the original on it...
 
So you'll save up for a scanner but you won't fix a $.50 light bulb?

I'm not trying to be a jerk, but...Pretty much everyone here has suggested you replace the lightbulb, but instead it appears you've spent probably $100 in parts, and are thinking about buying a $100+ scanner, and doing the work/spending the money on a replacement cat converter instead of replacing a 194 bulb??

If you intend to keep going at this rate, sell the TBI system and throw a carb on it, because you are utterly throwing money down the drain.

I'm happy to be helpful, but when you won't take advice, especially when it's so simple, it's sort of pointless to do anything other than show you the easy way out.

"Having a code really doesn't bother me"...I suggest you take the time to better understand the system. "Throwing a code" might save you from destroying your engine, or it may mean 8MPG instead of 15, and a terrible reduction in performance.
 
All the parts that I've put on were really necessary, regardless of the bad idle...it was still on stock wires, cap, rotor, O2 sensor, and coolant temp sensor. I'm more wondering why, after so many new parts, it's still not running correctly.

Having a code for the EGR system doesn't bother me, since the EGR system is worthless (yes, I know people here disagree, but that's my view on it). Having codes for otherissues would concern me, and I'll be getting a scanner as soon as possible. I've tried to take the instrument cluster out to replace the lightbulb, but the previous owner wired a bunch of junk up, and I'm still trying to sort the wiring out. The cluster is hung up on something, and until I get the time to clean all the wiring up (last few weekends have been busy), I can't put the new bulb in.
 
Hmmm,,,EGR system is worthless on a computer controlled system? ,,,,until the computer detects something is not right WITH the EGR system, and tries to make corrections through other electronic components to try to mke something work right that isn't there,,,then it just gets ALL screwy..

It WILL throw "other codes" as the computer is trying to correct an issue with a part you removed that it's tied into.

Honestly, if you don't think everything is tied together through that computer, and you think certain parts are worthless, you don't need TBI or any type of fuel injection,,,,

remove it and put on a carb setup, this is your most simple setup to use, and it seems you think this way too...
 
You want my .02? Most likey not but hey. I am the service manager at one of those overpriced S.O.B. Dealerships. I see this everyday. Someone has a ses or a poor running engine and starts throwing money at it until they want to pull there hair out. Then we bring them in and fix the whatever it is and I charge them a hour to DIAGNOSE the problem plus the fix. We had a customer replace 2 fuel pumps before he gave up and brought it in. Then we found the bad wire that was causing the partial connection I charged him $75 and he was out the door. The fuel pump was way more than the 1.5 hours I charged him. I used to do all my own repair and always had buddies with scan tool or used the paper clip trick but still sometimes it took me a while to get it right. Now I truly belive that it is best to pay the experts to do the repairs if you are in over your head. How much money have you spent? What if it was one $20 piece, but you have done everything but a engine rebuild and it is still not fixed. Why not have someone diagnose it and tell them you will do the parts replacement. You could have had it fixed and be loving your blazer not wanting to burn it to the ground. TBIs are in my opinion the best fuel injection chevy made for 2 reasons. 1) They rarely ever brake, they just run there are hundreds or 200K plus trucks running around here that run great (I just sold one and it still gets 17-18 mpg). 2) most of the time they are cheap to fix and simiple as heck. You wouldn't try and do your own brain surgery.
 
Element said:
I'm more wondering why, after so many new parts, it's still not running correctly.
Click to expand...
:haha: :rolleyes:

OK, I suppose replacing random stuff is a form of troubleshooting, it's just not a very efficient form.

When you removed the EGR valve, you did plug the vacuum lines that go to it, right?
 
Blue85 said:
:haha: :rolleyes:

OK, I suppose replacing random stuff is a form of troubleshooting, it's just not a very efficient form.

When you removed the EGR valve, you did plug the vacuum lines that go to it, right?
Click to expand...

on his EGR, that vacuum line *should* be going into a little sensor, that is also connected into the computer system, kinda tells the EGR when to operate the way it should...:wink1:
 
But what actually actuates the valve? Usually it is manifold vacuum, switched by a solenoid controlled by the ECU. If the ECU says "EGR open" and that vacuum is still there, that is a vacuum leak.
 
that's what i am saying, it's going to be your vacuum leak, then the engine may detect something else wrong because that vacuum leak is causing something else to get a funky reading, just throws everything into confusion.
 
also the egr on that system allows for some cylinder cooling at part throttle. This allow a bit more timing and mpg.
 
When the egr went bad on my S10 (2.8 tbi) it did the same thing. Coughed and sputtered barely wanted to run. Acted like the motor was flooding out.
 
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