Drivability Issue with new 350 in 1987 iroc

The combination is A 350 ZZ4 short block. AFR/Tpis cylinder heads 53CC chamber. Compression is10:8:1
running a Comp Cam Xtreme energy276. 224and 230 on exhaust @50. Lift is around 550" with my 1:6 rockers. I have a Holley Stealth Ram with a 52 mm TB. ADS 350 street Injectors running 49psi. Timing is set at 10 degrees base. Car barely idles and runs very rich. Throws a code 34. Everything like vacuum leaks and all the other possible problems have been checked. Is my problem something with a computer chip or the mass air. Code 34= low air flow indicated from Mass air sensor.

I would install a after market computer from F.A.S.T. There computers plug directly into the stock harness and is tunable by either a hand held, or a lap top. second replace the stock mass air with a unit from a later camaro like an LT1 car. all you will have to do is addapt a later plug into your harness to go with the sensor. when you get the car tuned out I think you will be verry happy with it.

James @ F-Rated Performance

I like your suggestions. But I just ordered the granatelli adjustable mass air sensor, the company says this will address my drivability concerns. Don't know if it will work? But I sure know it's got to be a better piece than the stock Bosch tpi unit. As far as the FAST management system. How much does it cost? And do you really think that this is my only option as far as optimum tuning. Thanks for the reply.

... Holley Stealth Ram with a 52 mm TB. ADS 350 street Injectors running 49psi. Timing is set at 10 degrees base...

Is 49psi with no vacuum? Too much pressure at idle, and or low vacuum will cause injectors to run rich at idle.

Did you set the minimum air and idle?

Do you also have the ADS Peformance chip?

Are the new injectors larger than stock? If yes, and no Performance chip, then did you update (reprogram) the ECM with the new injector size?

Set the base timing at 6° get it running right then you can bump it up where it gets happy.
Keep use posted, we'd like to the solutions to problems like this.

Unless i"m mistaken the the fast computer is about 6-700 and no its not the only way to go. But it is the best way to go incase you deside to change your setup later on. Yes the G Motorsports mass air unit will more than likely fix the problem you have right now but it won"t alow you to tune the ignition curve, injector timing, fuel curve, and cooling fan on/off, and weather conditions among other peramiters that will alow you to get the apsolute most from your combination. I would still get the mass air unit so you can at least drive the car. As for the timing I would run about 15 base, thats what I have my car set at and I have about 11.5 to 1 comp and 45-49 Psi. with no vacume is about the norm, with the vacume connected the pressure will be about 30 give or take at idle. with iron Vortec heads just run good fuel (93) and the car should be happy.

James @ F-Rated Performance

The problem is likely the chip programming - it's not compatible with the cam. I have a similar setup (cam and compression wise), and mine ran pig rich at first. The lower vacuum is causing the computer to add fuel. I'm running SD, so I can't help you with the MAF, but I would strongly suggest getting the car scanned / data logged - so you can see what's going on.

If you are not computer challenged, you can burn your own chip for the car. Check out thirdgen.org and moates.net for more information and the needed tools. I'm learning on my Z, and the improvements are noticeable.

Thanks. As far as fuel pressure goes I'm a little confused. The Holley stealthram fuel pressure regulator does not have a vacuum port on it like the factory setup. Ihave it set up at 49 psi. at idle is that too much? If I understand it correctly you are running 30 psi?

You might need to work with a tuner, give them the specs for your engine, and see what kind of a chip they can set you up with.

whats the car idleing at now?

sounds like it needs some computer tuning to me

OR

CARB IT :D :D :bow:

keep us posted man

I had a customer with this same problem with a 400 in an IROC once (when I worked at Jegs). After some digging, it appeared to be that the TPS voltage was set too high (.67 is the max) and it thought the throttle was open and it was not seeing the extra volume of expected air through the mass air meter. I won't say that is the problem or the only problem in your case, but I'd start there.

Thanks for all the feedback. But no I definately do not want to carb it. EFI in my opinion is the only way to go. Once it's tuned correctly there's no comparison as far as seat in your pants power compared to a dinosaur carburetor. Has any one used the granatelli adjustable mass air flow sensor in any of there buildups? If so tell me about it.

Thanks. As far as fuel pressure goes I'm a little confused. The Holley stealthram fuel pressure regulator does not have a vacuum port on it like the factory setup. Ihave it set up at 49 psi. at idle is that too much? If I understand it correctly you are running 30 psi?

The vacuum port is where the adjustment screw is....so when you're done adjusting pressure put the vacuum line back over the screw.

Wow that is one awesome Iroc Mr. Georgia. Just curious why you went with the holley 950 ECU. Coudnt you have got a custom chip to run the factory computer. My setup is almost identical to yours as far as the motor buildup. I can't wait for my chip to be burned by TPIS they are expensive but those guys seem very knowledgeable. They also said 30 LB. injectors would be overkill, why do you want to use them? Right now I just took the car out on its first run, my god the stock chip in this thing makes it run terrible. It feels so slow and pigish. I hope the chip wakes this expensive buildup run like it should!

Well, I was gonna go with the DIY prom burning route but after looking at the C950 and comparing the price and ease of tuning I decided against prom burning. Another thing was time...prom burning requires some in depth reading and understanding to make it work right and just didn't have time for that...plus I'm not exactly a computer savvy person. :D With my job requiring me to work odd hours, and going on the road for weeks at a time I'd rather not screw around with chips trying to get my car to run. Don't get me wrong though, I'm not dogging out prom burning....it's just not for me at this time. I will venture into it though at a later date when it's more convenient.

As someone mentioned above, check out thirdgen.org prom burning. Personally I would not pay for a "custom" chip, especially a TPIS chip. Do a search there and you will see why. :) For what they charge you for a chip you can buy your own equpiment and do it yourself, if you're willing to learn.

About the 30lb injectors...a datalog of one of my dragstrip passes showed my injector duty cycle hitting above 90% with 24lb inj's in the higher rpm ranges. A lot of it is because of the fairly large cam I have...remember you need to give the motor what it wants, not what you think it needs! This is why it's so important to either learn to burn chips/tune your ecm or find someone local to you that knows how....unless you send a chip burner a datalog of what your engine is doing, they'll never know that kind of info over the phone and they're just guessing on what they think you need.

Good luck with it!

Just wondering. I did order the custom prom burning from TPIS. But aside from that. Is that little chip that important. I built this motor with all the top shelf parts. I can't begin to tell you how upset I am with it's performance. I thought the ADS chip would have been adequate. Has anyone run into this situation,is it all the chip? Please give me some peace of mind! It feels like the car is a 305 out of a NYC taxi!!

Thanks. As far as fuel pressure goes I'm a little confused. The Holley stealthram fuel pressure regulator does not have a vacuum port on it like the factory setup. Ihave it set up at 49 psi. at idle is that too much? If I understand it correctly you are running 30 psi?

How do you figure? Mine has the vacuum port. You know tha thing you adjust for fuel pressure, that ist he port.

Just wondering. I did order the custom prom burning from TPIS. But aside from that. Is that little chip that important. I built this motor with all the top shelf parts. I can't begin to tell you how upset I am with it's performance. I thought the ADS chip would have been adequate. Has anyone run into this situation,is it all the chip? Please give me some peace of mind! It feels like the car is a 305 out of a NYC taxi!!

ADS or TPIS cannot do it that well. I would suggest you give www.fasterproms.com a call. They make a truely custom chip based on your specs and if you send them feedback by borrowng their DIACOM unit, they will keep tuning it till it is on. Same as dyno tuning except the road is your dyno. I have used their services for my car and have been happy with it. PM me if you need any more info on them

hey whats up? i see your from CT too...

Here's my thoughts... a friend of mine went through a simliar issue with his formula, bought a superchips chip, didnt work, then went to get it reburned, was told they didn't support it anymore.

DIY prom may be the best bet, Ed Wright is probably going to be your man...

the problem your having is not only with the fuel pressure, but with the injector size. There is an injector constant in the stock ecm and that has to be changed in order for the fuel tables to deliver the right amount of fuel. it will be intresting to see what happens with the new MAF you have on order, but the real issue is the injectors.

My suggestion is get talking with ed wright and cancel your order on the tpis chip... Ed has tuned a lot of cars and probably one with a very simliar setup to yours.

Steve

Yeh thanks alot. I did call Ed Wright at fastchips. He recomended 30lb. Ford motorsport injectors. I am also going to have them burn me a chip. I cancelled the TPIS chip and am going to send back the Granatelli adjustable mass air sensor. If you live in Connecticut should hookup in the spring hopefully my car will be running correctly. I'm curious, do you know of any chassis dynos around. I want to make sure the tune is on the money.

Stay away from tpis and their chips, they are clueless. You have a basic chip/mechanical issue to fix. Get with someone in an f-body club close to you who burns chips and do it the right way.

What do you think about ED Wright At fast chips in Oklahoma. By the way thanks for the heads up about TPIS. Nice GTA looks like a sleeper.

check out bristol dyno - check out www.ctfba.com too

www.bristoldyno.com

Whoever makes the chip for you, make sure they do it and then have the ability and will make reburns for you with feedback data. No one I know of is good enough to burn it right the first time.

Yeh just wanted to update my situation. Installed 30lb. Motorsport injectors and a custom prom burned by fast chip Ed Wright. The car finally woke up feels pretty strong. However, the torque converter is locking up way too early it even locks in 2nd gear! When going part throttle the car will shift very quickly and lock up in 2nd, 3rd,and OD. it feels like it could stall. Secondly have a problem on warm starts after running car just cranks. I have to step on the gas pedal to make it start. I have a feeling there has to be something going on with this new computer chip. I'm hoping that the people at fastchip will do the right thing and correct the problem. It never did this with the old prom. What do you guys think?

I thought that lockup is sent to the tranny from the ECM? How is it locking up in 2nd when it should have a certain parameter for deciding lockup and it does so in the Overdrive?

I'd make sure it is a truely custom chip and not some off the shelf unit. That is why I sent you to fasterproms. They burn you a chip and you hold on to it till the next one comes and so on till it is done and you send the lot back. No down time. That series of burns is about $350, AFAIK and the next series will cost you $150. Only time you need to reburn is if you do major work like heads, cam, intake.

It was too late by the time faster proms got back to me. I,m not understanding your synopsis on the lockup theory. Yes it is controlled by the ECM via the "prom". I can gaurantee you that I felt convertor locking up in second gear very strange. Ed Wright did custom burn this chip and I do beleive it is not a generic piece. They got all my specs on my combination when I faxed it over to them. Lockup is a parameter that can be changed when burning a chip right?

i would say talk to Ed first before discussing it here... lockup is an ecm function in your case. Usually it is set to unlock at certain throttle positions and speeds. Talk to Ed, he will work with you.

I dont even think the 4L60(700r4) can get lockup oil to the converter in second gear...huh? I did not think it is physically possible but I could be wrong...its known to happen with me time to time ;).

Later,

Erik

lockup of the convertor is predetermined by what speed you set the "lockup" at in the chip. For instants, in my car, I have to set it at 53mph since I did a gear swap. if I leave it at the factory 35mph it actually locks up at about 27 (3.73 gears). The car lugs and I have to keep it in 3rd just to keep the R's up so it won't lug.

Yes just want to give you my current dillemma. I sent the prom back to ed wright they did straighten out the lockup to only come on at 50 Mph. However I am not sure about the air fuel delivery. I think it's running too rich. Does anyone run 30lb motorsport injectors? While monitoring my injector pulse width with the X-ray scanner It was something like over 5.0 -6.0 volts at 3/4 throttle- full. My stoichiometric gauge in the car was lit full rich. Also the plugs look very black sooty. Is a wideband chassis dyno in order. What suggestions for tuning Timing, fuel pressure, Tps etc.. might you have. I got to have this car in perfect tune before taking it to the track. Hoping to go low 12,s.

Does anyone run 30lb motorsport injectors?

While monitoring my injector pulse width with the X-ray scanner It was something like over 5.0 -6.0 volts at 3/4 throttle- full.

My stoichiometric gauge in the car was lit full rich. Also the plugs look very black sooty.

Is a wideband chassis dyno in order.

What suggestions for tuning Timing, fuel pressure, Tps etc.. might you have.

I have run them with no problems. You need to set the EPROM to 30# in the injector size setting. Currently I am running at stock pressure FMS injectors that are 42 pph.

Pulse Width is measured in miliseonds not voltage. What is your O2 sensor voltage? AFAIK, the o2 sensor will read between 0 - 1 V. At idle, my pulse width is about 1.4-1.6 miliseconds. Not sure what yours should be. It depends on the setting in the EPROM.

If your plugs are sooty then it is running too rich. A properly adjusted chip will not run too rich.

I never had my car tuned with a wideband O2 sensor. I had it on the dyno with the sensor I am running. With Fasterproms, I used the road as my dyno and with Hitechmotorsport, I used a chasis dyno because I wanted a HP number.

Timing should be set at 6 deg or whatever Ed recommends. Mine is set for 6 deg because that is what the EPROM is basing it off. To get it to idle right, you have to set the IAC to say 10-20 counts after it is warmed up and in closed loop. Then you set the TPS to whatever Ed tells you to. Mine are all set to stock settings of .54V

Thank you I stand corrected about the injector pulsewidth. I gather the fuel pressure should be 38-42 psi. with the vacuum line on, correct. I was not able to monitor the o2 sensor at wide open throttle. The injectors were at the same values you stated at idle but what about 3/4 to full throttle. What kind of values am I looking for from the important sensors such as o2, injector pulsewidth, timing advance. Also a gray area for me is setting base timing. What difference does it make if your setting the timing at 10 degrees BTDC or 6. I thought all the advance if needed is controlled by the computer. Oh do you think that if my fuel pressure is too high or timing is too advanced that this could be why my plugs are sooty? Thanks for all your help.

Fuel presure is measured with the hose OFF!

Don't know what the pulse width should be at 3/4 throttle. It depends on your combination and how the person sets it up. That is why I take Diacom readings and send it to Fasterproms. So they can see what the car is doing at idle, mid range, wot and cruising. They can adjust the pulse width based on what they see going on.

It makes a difference to your result. The ECM is stupid. It doesn't know what timing is set at. If you program it so that it assumes it is 6 and you give it 2 then it will advance to what it thinks is say 30 deg when it is actually 26. Think of it like your check register. If it says you have $30 and you write a check for $25, you should have $5 left, right? If you screwed up and log $30 when you have $10 and write a check for $25, it will bounce.

If the fuel pressure is too high, you could have sooty plugs because there is unburnt fuel. Your headers could glow red too. If your timing is too advanced, you might have other issues. Make sure it is at 6 deg with the wire disconnectd.

change your plugs or clean them up....i am having same problem.......

If you have access to a scanner, log some data, then plot it on a spreadsheet and send it to ed wright after you have checked the basics, like tps voltage correct and idle air speed set correctly, cleaned iac motor, no vacuum leaks, fuel pressure at 42 psi. Ed assumes that your pressure is at stock levels and the initial timing is at 6.

It sounds like you have a vacuum leak to me or something isn't adjusted right, computer controlled cars only know what the sensors tell them, they are not 'smart'.

Also if you don't have an aftermarket ignition box, then put some new plugs in.

Ok I,m going to get the car back down to 6 degrees base timing. But the fuel pressure? With the vacuum line OFF I should set it at 38 - 42 psi? Then when connected the fuel pressure will drop even more? I,m going to have the car on the chassis dyno with the wideband 02 on tuesday.

Ok I,m going to get the car back down to 6 degrees base timing.

But the fuel pressure? With the vacuum line OFF I should set it at 38 - 42 psi? Then when connected the fuel pressure will drop even more?

I,m going to have the car on the chassis dyno with the wideband 02 on tuesday.

That is correct.

That is correct too. With the hose off, there is no vacuum. Of there is no vacuum in the manifold, what conditions exist? Probably WOT. With the hose in place, you are signalling that you have less than WOT conditions. Less than WOT means what? You will not need as much fuel so the pressure is lessened.

Ok. Your call. I never had to use a wideband sensor. With fasterproms, the road was my dyno and it worked perfectly.