So picked up this nice looking 87 iroc 5.7 previous owner says it needed a good tune up to run right but he didn't have the time.I thought should be simple.So as far it goes it has new fuel pump, new injectors however 2 are showing ohms of 13 the rest are 16.New tps which is set right.New iac.New pvc and new maf ,and lastly new distributor .Timing set at 6 degrees before.Guess what after it warms up it surges up and down wtf.Im so close to making it a carb unit.Final not fuel pressure is fine hold good.Any good thoughts would help.

 

Injectors shouldn’t vary more than .5 from each other if new or a ohmed and flow matched set. What is int/Blm showing while during high ?

 

Any codes?

Sounds like it could be a bad O2 sensor.

 

Those two injectors are probably bad. Get a fresh set of Delphis from Southbay.

 

no codes

 

No o2 sensor on it that I'm aware of as it has headers

 

I have no way of testing for that

 

I have my old set and some are good could I not just replace the bad ones and see what happens

 

Still should have an O2 even with headers. There was one originally and most aftermarket headers have the bung for it. If someone just took it off that would cause an issue.

 

would that not flag a code ? I don't have any.

 

I would think so, maybe you have an ECM issue also or maybe the light on the dash does not work. I do know that an O2 sensor should be part of your original system/wiring harness so unless someone somehow burned a new chip to remove the O2 circuit it would cause the engine not to run properly.

 

You might consider buying a scanner snapon mt2500 or datalog cable so you can try to see what’s going on. With headers the o2 might not be how enough to go into closed loop. Acdelco afs74 and there’s a pigtail on Amazon .
I wouldn’t use unmatched used injectors . Wasted effort.

 

lights on dash works jumped the port and no codes

 

A missing o2 will not throw a code, just won’t have closed loop.

 

how important is the egr vacuum solenoid I know it's not working and impossible to find.The more I keep thinking about an efi to carb swap is in the future ...lastly my garage mechanic said start looking for vacuum leaks.

 

It’s ran off ported vacuum, unless egr is physically stuck open this leak is not effected idle but may want to plug under the tb.

 

well think I may have found the problem.Looks like the o2 sensors are not connected .Matter of fact there in the ele trial connector and not even installed in the header. Why would previous owner do that.

 

I've got a 87 iroc with a 5.7. Same issues and I can't figure it out. I'm so close to just putting a new holley computer and harness.

 

Hey im with you on that.However i put new gaskets on the plenum ect.I noticed the bolts were not even tightened and gaskets were old when previous owner put in new injectors plus one of the gaskets was incorrect.So after I put it back tigeather seems to run ok.Juat going to set the idle and timing and see how it runs.

 

Started working on mine today, I'm doing headers 3.5" exhaust, msd billet distributor and wires. While I'm doing that I'm going to go over everything. At the point when I get it back together and it keeps acting up I will do something different. This cars been nothing but trouble since I bought it. I believe these motors are just prone to crap because of the crappy computer systems.

 

nothing wrong with the 1227165 ecm , might need to educate yourself with efi

 

So it's not outdated? No doubt I need to learn more about efi but to invest in a out dated ecm seems silly.

 

ive been told go carburetor save yourself alot of heart ache it it wi go like stink.My neighborhood down the road had issue with his camaro so that's what he did .Doesn't regret it.Better than beating your head against a wall.Funny thing is my other tech guy had a 87 he stated nothing but issues with the efi system so again he switched to carb.Inasked him if he lwould look at mine and he kindly refused lol.I will also ad I pulled #1plug and it's black over rich idle.issue.

 

I don't feel it's a problem with the OBD 1 EFI systems. Alot of us here including me have the TPI working like it should. Infact I would argue that more of us retained the system instead of switching to carb. The problem is we are dealing with 30-40 year old vehicles, most neglected or hacked through the years. Take a 2020 vehicle and neglect it for say 35 yrs. and 5 owners, would the new tech save it from the issues we experience? Dout it. We are older and carbs were the tech we know so I get it. The 2020 vehicle with EFI problems would you throw a carb on it? Dout it. So I have to ask, if our systems are outdated and not worth saving why would you go backwards in technology and the downsides of carbs. You need knowledge of tunning carbs so to throw a Holley 750DP might make it run just as bad if not tuned properly for your engine. Knowledge is the key to all of this.

The answer to all of these TPI problems is being able to datalog the ECM. The problem with our EFI system is this is not easily done, but if you are willing to learn it will pay off 10 fold!

 

good advice, if your taking the easy way out that’s a huge expense instead of learning what you have and it’s capabilities. Unless the wiring is completely hacked and other underlying problems fix and enjoy what you have you will be way better off than a carb.

 

I understand what your saying but even a Ace a mechanic with all the tools inbthe trade wants nothing to do with because hes been down that road before and even changed it over because it drove him bonkers what does it tell you.

 

Sounds like you need to educate yourself too or find a different mechanic .
I don’t get why you even post in the tpi section if your not wanting to keep it .

 

I will say this does seem to be a common problem with mechanics nowadays. Ace or not, tools or not they are just not willing to diagnose a problem if they can't hook a computer to tell them what is wrong. Alot of so called ACE mechanics are no more than just parts changers. I would call it lazy but time is money so I see why mechanics are not willing to learn any more. Hell find a mechanic nowadys that will rebuild a carb, nope just buy a new one its easier. What does that have to say about today's mechanic?

 

oh I'd.like to keep FEI however il not going spin my wheels and spend stupid money trying to figure it our.As for my mechanic he's A 1 just knows when to admit defeat .lol
well just an update I think problem is solved.I changed all the plugs which were ngk to ac delco r43ts.The ngk were fubar totally black rich carbon.No wonder couldn't get a decent spark.No idles decent for now.

 

Well i thought i had it fixed got down the road and same.**** rough idling and popping through exhaust grrrr.Went and purchased new o2 sensor old one totally caked with black soot obviously running rich .Immm. stumped.Any thoughts .

 

My thoughts are you have 2 unacceptable injectors and I'm suspicious that you have the wrong ones. A datalog would be helpful.

 

what's your fuel pressure? Is the regulator leaking fuel into the vacuum line?

 

ecm data would be helpful to see what the ecm is seeing. Are the injectors a matched flowed set ? Where were they purchased from?
any fuel in for vacuum line ?

 

fuel pressure is good and holding

 

I don't have the means to collect the data.Yes the injectors are a matched flow set .I do know that 2 vary in ohms from the others 6 are 16 the other 2 are 12 but I was told that shouldn't cause an issue .They are supposedly new Fote-d5 injectors.Its a Ford part # But bosh plugs 19ibs per hour though thats meant for a 305 mine supposed to have 22 not sure if that makes a dif

 

no idea where purchased and no fuel in vacuum lines

 

If the computer isn't tuned for those then thats a problem.

 

does it need to be tuned ? I thought it being a 87 it's just plug n play injectors and nothing required

 

Delphis or tune D3 but they’re kinda noisy. There’s tons of junk injectors on eBay not real and don’t tune. It’s amazing they sell such crud

https://www.ebay.com/itm/35330413181...mis&media=COPY

 

So are you suggesting new injectors..?

 

Idk what the ecm is doing but quality injectors would be a great start to resolve running issues.

 

I think so. your 5.7 should have #22 lbs injectors designed for GM applications. Your ECM controls certain functions of the injectors and if they are not matched to the computer who knows how much or how little they are flowing. The Delphi #22 lbs are the only ones that are considered direct replacements that would not require a "tune".
22LB DELPHI CORVETTE CAMARO FIREBIRD 5.7 TPI INJECTORS 1986-1992 (southbayfuelinjectors.com)
IMHO I believe that those wrong injectors you have is what is causing your rich condition.

 

well the delphi at southbay is 435 bucks thats 589 bucks canadian and not sure that will fix the issues.I could spend that towards a carb system and stop chasing my tail lol

 

Southbay offers TGO members a 10% discount if that helps any. I think the code is "tg11".

 

Code does not work

 

looks like I'll be buying some new injectors after all.I took the old ones out and apparently there for a BMW and has 4 holes.Why would some idiot do that. No wonder it runs like crap

 

I think code is for refurbished cleaned and flowed injectors only.
you can make other applications injectors work but it takes some tuning .

 

https://www.thirdgen.org/forums/afte...romo-code.html judging by the thread, I'd think it would work.

 

Good to know I thought it was on select items .

 

I've used the code several times to get the Delphi injectors and other things from SouthBay. Sometimes they have problems with the website. A call to them should fix things.