schroeder178

Finally after 2 years i bought new injectors for my 350 iroc, ever since i put them in when you first start it it idles super high and kinda settles down and then rockets up again. after a while it calms down to normal, then it will run super rich and hardly idle and stutter and shutter and run rough. but when your driving down the road it runs great...and its getting 10 mpg, which before it was getting around 14, what have i done?? it has a maf code and egr code but before the injector swap it idled 10 times better and got better fuel milage.. any ideas?? thanks

jamon8

iTrader: (3)

what kind of injectors were they

89transam*pearl

iTrader: (1)

Sounds like the EGR valve as mine has the surging idle at start up also. Just received an OEM AC Delco EGR valve from Ebay and plan on installing it in the morning, I'll let you know if that solved the problem.

ronaldgtp

had the same problem with my 90 iroc for year put in south bay inject runs great also put in new fuel pump and screen.screen was starting to fall apart.
did you ohm out he injectors to check them out.one of mine was really bad.

greenyone

iTrader: (1)

I agree with *pearl. If you have a vacuum tester/brake bleeder, hook it up to the EGR vac port, give it a few bars of vacuum and see if it holds. If you don't have a vac hand pump, get one. Mine did the same thing with the idle surge at start-up and the EGR was junk.

schroeder178

Yeah knowing the injector might help, they are Bosch 3 22 lbs injectors. And I know the egr don't work at all because the temp sensor wire went MIA and I can't find it for the life of me haha. But even before the injector swap it idled better and got better fuel milage... I mean sometimes the car barely idles it shakes and runs super rich all the time. And then sometimes it idles fine...I read somewhere about ruining the IAC if you don't clean your throttle body right with brake cleaner and I think I could have ruined it...what's the symptoms of a faulty IAC??

greenyone

iTrader: (1)

It's possible that it's IAC, but since you just changed out your injectors I'd lean more toward the possibility that you created a vacuum leak somewhere in the intake when you did the swap.

schroeder178

I've checked so many times for vac leaks. I'm gonna buy new gaskets and see if that changes anything... That or a injector is not getting a good connection

paulo57509

Where did you get the injectors from?

How long did the injectors sit on your shelf before you installed them?

I let some cleaned and flow matched injectors (from Fuel Injector Connection) sit on the shelf for months (might have been a year) before I installed them. I couldn't even get it to idle. I didn't even bother backing it out of the garage. By the appearance of the plugs, it looks like some of the injectors stuck closed and some stuck open (might have been the ECM trying to over compensate for the stuck closed injectors).

New plugs; zero miles

schroeder178

I bought them from southbay. And the day after I got them I put them in. The car runs wide open great it just hardly idles and runs super rich. Burns your nose and everyone elses around you. The only thing I did when I put the injectors in was clean the throttle body and I sprayed a ton of brake cleaner down in the iac not knowing you cant do that and I read that ruins them. A few days ago I went all the way down to the injectors again and back up and its still doing it.

greenyone

iTrader: (1)

I'm sure that if you have a faulty injector(s), that Southbay with their reputation will rectify that problem if you contact them for some product support, but you really need to fix the other issues too. That ECM will constantly try to compensate for other faults in the system and you did mention that you have existing EGR and MAF codes. I'd replace whatever components are giving you fault codes and work out from there.

schroeder178

I bought a new IAC and adjusted the minimum air and it idles way smoother. I have it set a little high yet but I can't tell what rpm to set it at because my tach is way off. But that seemed to have cured the idling problem!

camarofvr

Did you try resetting the ecm? I changed to bosch III's and mine ran like crap and sounded awful, so I reset it and took it around the block. It still ran rough at first but I pulled over and let it idle for a minute and it all of a sudden smoothed out and ran great.

schroeder178

No I hadn't but now the minimum air adjustment is way off and the IAC I can't adjust right and the tps is out of whack. So for now the IAC is fully extended and unplugged and it's just running off the butterflies until I can afford to have someone take a look at it... :\ but since then the ecm has been reset

camarofvr

The IAC should take care of most of the idling. It only needs the minimum idle(which is impossible to set without an accurate tach). That's probably why you're having problems. I adjusted mine to idle it up and it wouldn't idle smoothly. I guess the IAC was having a problem with where I had the adjuster screw so I kept backing it off till it sounded about right and kept backing it off till it felt right when I had it in drive at a stop.

schroeder178

How exactly did you set it? I know the right way how to do it but I'm just curious if you did it a different way

camarofvr

Just backed off the torx screw on throttle body. If it's too open the iac seems to fight with it trying to correct itself.

schroeder178

Did you ground out the aldl let the IAC extend and then in plug it to set it or just adjust it? And then what did you do about the tps?? All of my adjustments are so off its stupid and for the life of me can't get the tps in the right spot

camarofvr

No I bought a new one since the old one fell into three pieces when I took it off and it just plug and played. Don't know if I just got lucky or what but I figured if it didn't work right out the box I'd adjust it afterwards. Tps is bit of a pain to set but there are a lot of videos out there on how to do it. The hardest part for me was that I was using a cheapo multimeter.

schroeder178

Ah I see. I can fiddle with it for hours and just go in circles... I need to get a baseline to start with and go from there or something. It runs great down the road just won't idle and runs rich and misses. Smells like the ecm is choking the motor out with fuel..

camarofvr

All that flooding could have fouled your plugs. I'd check them.

schroeder178

Yeah I have new plugs for it i was gonna wait to put them in until I get it running right tho. I pulled one and it didn't look bad at all

camarofvr

Don't know how important this is but my haynes manual said to do this:

schroeder178

That actually might have just helped alot! Thanks man. Hopefully that will help get it closer in the ball park

schroeder178

What would the symptoms be if the orginal injector o ring is stuck in the fuel rail...?

camarofvr

Run like crap and/or leaks. The only good thing about that is it has nowhere to go but down thanks to the pressure so you'd find it fairly easily after removing the fuel rail. But since it only gives you a problem at idle I doubt that's it.

schroeder178

yeah, it runs great down the road just idles like hell. sometimes smooth sometimes not. IAC is unplugged, seems to run better with it with the iac extended for some reason, and its a new iac... would you think a bad maf would cause this? never had this problem before the swap but its always had a maf code since about a month after I bought it...

alex722607

iTrader: (3)

I think I am in the exact same boat as you. I changed my injectors in May and I have had issues with it ever since. I thought I had a vacuum leak so I changed the gaskets ... I went through three sets. After doing it so many times, the heads of the bolts were getting beat up, so I got new bolts from Hawks, put them in and torqued them. BIG Mistake. The heads all stripped.... WTF. So I talked to Southbay about the possibility of the injectors being faulty, so they said they would flow test them. Only one problem I can't get them out. I need to drill out every single bolt. I did five and it took me 5 hours. (I was careful because I did not want to screw up the threads on the plenum.)
And one of them won't come out because the bit broke off inside the head of the bolt. But what do you expect from Harbor Freight. I did not even think twice about the EGR though, you may have something there. I know that mine was bypassed at some point because it was malfunctioning, and my issues are extremely similar to yours. For me though, since I am not going to be playing with this in the near future, I had to bump base idle and the timing just a bit so I could drive it.

schroeder178

I haven't screwed with it either hardly, I don't think its the egr causing this because when I pulled into the shop to swap injectors the car ran great and idled great, the next day after I finished it went to hell. When I did the swap I pulled off the throttle body to clean carbon build up off off it, plus I had new gaskets so I figured I'd do it all. At first I thought the IAC was ruined because I used brake cleaner to clean it and didn't remove the IAC, bought a new one and changed nothing. New gaskets? Nope nothing. If I set idle with IAC unplugged and extended I can at least drive it around but with IAC plugged in, forget about it. I am too wondering if there's a faulty injector... What injectors did you use? I used the Bosch 3s from southbay. This whole problem is driving me crazy...

schroeder178

bad maf? IAT sensor, CTS sensor? anyone have any other ideas??

ASE doc

I can't advise you on what way to go until you provide more information. Guessing and replacing parts gets expensive and the last 3rd gen IROC I had in for a MAF code (34) was just poor contact at the sensor connector. No amount of new sensors would have ever solved that. I found the problem by running through the trouble tree for the code that I pulled from the ECM. That's where you need to start. It sounds like you've pulled codes. Now you need to complete the test sequence for each code that you pulled. You will probably find a poor ground connection somewhere that you over looked on reassembling the intake. You may even have a broken wire or a pulled out connector. These are old cars and the wiring can be a problem. Generally, any problem that starts after a repair is caused by something we overlooked. Running through the diagnostic tree for the codes you have will probably point you towards a solution.

If you don't have a service manual for the car, I suggest you get one. I like the Helms factory shop manual. It is the same book we used at the dealership. There is no better resource for service info. Of course these books are pricey. You can probably get by with a Haynes or Chilton. Either of these should have the factory trouble code testing trees. Most of the factory trouble code tests require either a test light or a DVOM. Be sure you have a good DVOM with 10 megaohm input impedance, or you may get false readings. Some tests require the use of a factory compatible scan tool. Personally, I couldn't imaging diagnosing any electronic fuel injected engine without a compatible scan tool, but you can probably get by without one for the codes you have.

BTW, just because there is an EGR diagnostic temp switch fault doesn't mean the system doesn't still operate. In fact, the valve could be stuck open, causing your poor idle. Using a hand vacuum pump to open and then release the valve is one step in checking for this. I posted a method that I have found successful for solving code 13 when replacing the EGR diagnostic switch isn't practical. In the thread there are also postings of replacement temp switches for those looking to properly repair the EGR system. The temp switch system was a problem for GM, as it can set code 13 even under normal operation. They deleted the switch after a few years.

If you have been driving the car with a MAF failure code and wonder why it suddenly got worse after replacing injectors, just be aware that, in the first place, ignoring a failure and trying to improve performance by working around the problem is just asking for more problems. It rarely works out. When there is a MAF failure code current in the ECM, it will deliver fuel according to a preset, default fuel map that is stored in the MEMCAL of the ECM. This default map is designed to just keep the car running long enough to get to a repair shop. On you old injectors, it was probably a little too lean because the injectors were crap. Now that you have new injectors that deliver fuel the way they were designed to, the MEMCAL map is too rich. The solution for this is to repair the MAF system, and any other faults, so that the ECM can properly adapt to the new injectors and operate the way it was designed to.

schroeder178

that whole last part just might have hit the nail in the head...ive done a lot of looking around checking wiring, ive pulled the injectors out and re installed them, followed a diagnostics tree for the code 34 and it led me to the maf being bad. Egr code is no more, I found the wire a mechanic grounded that goes to the egr temp switch and connected it back. so it looks like a bad maf after all... I mean it sounds like the car is drowning in fuel at idle and misses, but going down the road it cleans out. thanks

alex722607

iTrader: (3)

now the question is where do you get a quality maf and not give an arm and a leg for it? .

ASE doc

My car runs an aftermarket, laptop programmable speed density system, so I don't have that problem. I also have true ram air and a 4" tube to the TB from a modified high flow air filter housing. The problem with these early EFI vehicles is availability of the long obsolete control hardware, i.e. sensors. I had an 87 Buick in the shop last year, owner just loves the old pile, that went through two A1 Cardone MAFs(NAPA reman electronics are A1 Cardone) in as many months. The one that was on it when it first came in was only a few years old(NAPA also) with no more than 10K miles on it.

Unfortunately, until a true quality focused, preferably domestic, rebuilder becomes interested in providing these assemblies, there isn't much choice. My system, ACCEL DFI gen 6, was pricey, took alot of wiring work and engineering to integrate into the factory system, and is no longer available. However, the 90-92 cars were also speed density and most GM models(S-10s for instance) used the same ECM. There is alot of information available on performing the conversion over the DIY PROM section of this forum. RBob is very sharp in this area. In the meantime, try to find an NOS part or take your chances on the remans. At least most remans come with a 1 year warranty so if it fails right away, you can get it replaced. Someone like Autozone might even offer a lifetime warranty.

In fact, it's been a while since I did a web search for one of these parts. You may want to start there. There may already be better options in the rebuilt arena. If AC Delco, or Standard Motor Products offers the part, either one is a good way to go. These two companies seem to take engineering and product quality seriously.

86White_T/A305

Just fyi when you set the iac and tps you dont need a tach to set it properly.I much rather use a multimeter. It helps to sometimes elongate the screw holes on the tps to get it perfectly set.As for the iac setup i do all the steps you mentioned with resetting it jumping the aldl etc but I set the minimum air with the car in reverse or drive with someone either in the car on the brake or if your handbrake is strong then use that and I adjust so it doesnt stall.That way in park/idle was perfect. I think your tps is out of adjustment which makes setting the iac that much harder and the ecm is picky about theyre relationship.Get those 2 squared up and move along to chasing down other gremlims.

ASE doc

I personally prefer to use either a tach doing the minimum idle setting as described in the service information, or just use my scan tool to perform the minimum idle air setting with rpm data and TPS voltage on the screen in front of me. As far as TPS goes, there is a line right at the 88-89 model year split where GM went away from the adjustable TPS and to a fully adaptive closed throttle strategy. On the later TPS's, anywhere below 1 volt was acceptable, so long as the ECM always reads CT with the throttle released. To know which yours is, you can look for the adjustable(early) TPS or refer to the service information for your model year.

86White_T/A305

The main reason I dont use the tach is because how often they can be slightly off on our cars,but having a scan tool works..if not..multimeter and either will be spot on.Not many people have scan tools for the old aldl ports these days but a cheap multimeter can be had anywhere.

Been awhile since ive had to deal with tpi issues but not sure if brake clean is actually bad for the iac when cleaning the tb.Ive always used throttle body cleaner which was sensor safe. Hope you get things ironed out with little hassle OP

alex722607

iTrader: (3)

Reading this over just reminds me of how touchy TPI can be.

86White_T/A305

Its a good learning experience though,alot of techs these days are lost without a scan tool/app to trouble shoot issues and still dont understand that replacing parts doesnt solve problems until you figure out what the initial cause lead to a part failure.

I will say dont stress out..its not a overly complicated system.The issue will probably be minor. I remember how much my tpi/hsr setup was a chore to get going 100% but it made dealing with my ls swap a breeze.

Veaceonee

iTrader: (1)

You don't need a fancy scan tool like a Tech1 or something. Just get an old laptop or netbook, an ALDL cable (kinda pricey here), and WinALDL (free) or any other diagnostic program. Instantly know exactly what the car is doing in real time. It will help eliminate all the speculation. Saved me a lot of time.

ASE doc

The old Snap On brick has all the functionality of the Tech1. These were obsoleted by Snappy about 10 years ago and can be purchased for about $300 on ebay or Craigslist. Just be sure the tool comes with the domestic software cartrides, a good cable, the GM 12 pin ALDL adapter, and a power cord. These were standard with the tools and should be there.

I am a professional technician and a diagnostic specialist since 1990, starting with GM. I use my scan tool and other equipment, not to find out what part to throw at a problem, but to isolate the actual cause of the problem. If you think that this industry and use of equipment is about swapping parts, well sadly, you're largely correct.

However, real master technicians still take the time to test and verify the cause of a failure before replacing parts. You can do this without a scan tool. The scan tool just makes the process alot more straightforward. Of course, alot of what the scan tool shows you will make no sense to most people, and these early(OBDI) GMs used terminology that is exclusive to a narrow year range of vehicles. Even I have to remember each time I get one of these in what the differences are. To make use of the information, you need to educate yourself on what it all means and how each data PID relates to the others and how it can affect engine performance.

FYI, the last 3rd gen f-body(an 88 IROC 5.0TPI) I had in the shop had codes 32 and 34 current. I repaired both faults and restored normal engine performance without replacing a single part.

EDIT: One thing I want to add to my rant is a little thing known as FFT(fixed first time) this is a rating of a technician's diagnostic accuracy. The public isn't savvy to this information. Repair centers want you to think everyone there is a master mechanic. FFT is the percentage of vehicles that were correctly diagnosed and repaired the first time. My rating is at 97%. This means that 97 out of 100 cars were diagnosed spot on. The other 3 percent are vehicles where I missed something and had to go back and retest. The vehicle still left with the problem fixed. It just took some hair pulling and swearing on my part to get it there. Some guys will shotgun a diagnosis, recommending alot more than just what they think the problem is, trying not to have the car come back. Everyone hates comebacks and of course the service writer loves it when we hand in a repair order with big bucks worth of recommendations. It's the customer that gets hammered with more repairs than his car really needs, just because the tech isn't really sure. I do not do this. I will spend the extra time to isolate the cause of the fault, and if I can't isolate it, I will say so. My record is good enough that I can say "I don't know" and if the SW doesn't like it, he can kiss my ***.

Jersey89GTA

iTrader: (1)

Didn't read this verbatim, but manual says to set IAC length to 1 1/8" from pintle to gasket.

TPS set to .54v to .59.

ASE doc

My information states .54 +/- .08 volts. The key is to have TPS centered around .5 volts. TPS is adjusted after minimum air. The manual method of setting IAC pintle depth works fine. But I believe a compatible scan tool will perform an IAC reset which does the same thing.

schroeder178

I did a diagnostics tree and cleared the ecm, started it, set code 34, unplugged maf, got code 33, and checked voltage to the maf and got 14 volts to the red wire and I believe 4.9 to the green, I ordered a used bosch off ebay from tpi parts that was a known working unit to see if that helps, theres no code 36 but I don't hear the burnoff relays clicking...like I said the motor cleans out great going down the road, doesn't skip a beat. just idles and misses and runs horribly rich. the motor runs the same with maf plugged in and maf unplugged, no difference.

ASE doc

Sounds like you're on the right track. Just use the trouble tree and diagrams to zero in the problem. I go past the trouble tree myself, using my voltmeter or lab scope to back probe the MAF signal circuit to see what actual MAF voltage is. This shows me more of what's going on there. Remember too, a good ground is just as vital as the power and signal circuits. If the ground is open or high resistance, it will tend to cause high MAF voltage. The trouble tree should include testing of the ground circuit.

schroeder178

Do you know where the ground is for the maf circut? And if it was a grounding issue, wouldn't it set a high maf voltage code?? Or a code 34 like I got

ASE doc

Okay, I read code 33 in your last post. I see now you got that code with the MAF unplugged. The MAF signal ground is at the ECM. The MAF power ground is at G118 at the rear of the passenger side cylinder head. The body ground strap attaches at the same place if that helps. MAF low could be cased by a dirty sensor. Make a back probe from a paper clip. Sharpen one end and carefully insert it beside the signal wire, inside the weatherpack seal, at wire side of MAF connector. Plug the connector in and use an alligator clip to connect your DVOM red lead to the paper clip. Watch voltage with the key on, after you start the engine and as you run it up to 2,500 rpm. You should get about .5 volts with the key on. About 1.6 volts with the engine at idle, and about 2.5 to 3.0 volts at 2,500.

Just checked the trouble tree for code 34. They don't give you much room there. By what you already verified, you need a MAF sensor. The method I've posted for measuring MAF voltage is just one way that I verify MAF signal on the hot wire analog sensors. This is another place where a scan tool is very useful. Scan data shows MAF voltage and MAF grams per second. You can quickly see what the sensor is doing and if the fault is current, whether the sensor is inop or just reading low.

schroeder178

I did that and at idle its showing like 2.56 volts. runs no different with it unplugged, switched the burnoff and power relays, no difference. then just to see I unplugged fuel pump relay, started, surprisingly ran better but was blowin smoke out the back and still ran rough, and I plugged the maf in and the car died. I dunno if that means anything but that's the only time ive gotten it to do anything with the maf being unplugged or plugged in.

schroeder178

also I cant tell where the idle is on my car cause the tach is off but it was idling high

schroeder178

with the key on unplugged I get 4.9 volts to terminal c, plugged in it drops to 2.4 just with the key on. And there is no power to the red wire until car is running. With the car running it gets 13.6 volts to the red wire and the green wire goes from anywhere between 0.40 to 0.90 but never above 1.00 volts when im revving it up. at idle its at about 0.50 volts. im guessing the maf is toasted