Hard to start with new maf
#1
Hard to start with new maf
Howdy,
i bought an 88 gta with the 350 in it. When I bought it the maf was unplugged and the car would fire right up. I replaced the maf and it’s relay cleared the check engine light but now it is a bear to cold start. After it warms up it’s not a problem but sitting overnight it takes a minute or so to get it to fire. Any ideas would be greatly appreciated
i bought an 88 gta with the 350 in it. When I bought it the maf was unplugged and the car would fire right up. I replaced the maf and it’s relay cleared the check engine light but now it is a bear to cold start. After it warms up it’s not a problem but sitting overnight it takes a minute or so to get it to fire. Any ideas would be greatly appreciated
#2
Supreme Member
iTrader: (1)
Re: Hard to start with new maf
There's a lot of terrible MAF's out there. They really don't make a quality unit for these cars anymore. Best solution is to scrap the MAF system and go to speed density. Dynamic EFI has a plug-and-play for this:
https://www.dynamicefi.com/EBL_Flash.php
GD
https://www.dynamicefi.com/EBL_Flash.php
GD
#3
Senior Member
Re: Hard to start with new maf
I have a Delphi MAF I bought from Rockauto a couple months back. It seems to be working fine.
#4
Senior Member
Re: Hard to start with new maf
I don't see how a MAF would interfere with starting. When you first start up cold, the ecu is in open loop, so isn't it just looking at the TPS and using tables until the thing warms up and goes into closed loop?
I also have heard that there are some really shitty MAFs on the market now, but that Delphi which I'm running, so far, has worked well.
Some guy over in Holland rebuilds Bosch hot wire MAFs, but you could buy 2 or 3 brand new Delphi units for the price he charges to rebuild a Bosch.
I also have heard that there are some really shitty MAFs on the market now, but that Delphi which I'm running, so far, has worked well.
Some guy over in Holland rebuilds Bosch hot wire MAFs, but you could buy 2 or 3 brand new Delphi units for the price he charges to rebuild a Bosch.
#5
Supreme Member
iTrader: (1)
Re: Hard to start with new maf
I think it has to do with the relay he replaced along with the MAF - IIRC the fuel pump power goes through the MAF relay also. Probably the aftermarket relay has something to do with the issue. So it's now relying on the oil pressure switch to power the fuel pump which takes a bunch of cranking.....
GD
GD
Last edited by GeneralDisorder; 05-21-2019 at 08:00 PM.
#6
Junior Member
Re: Hard to start with new maf
I have a few relays that all test good even under load and yet they will make the car run rougher/smoother on startup. you can try swapping your relays (the two that are the same). and perhaps this is due to the aftermarket relays not being 100% original. There is a resistor(?) missing in the new ones. You can see it missing on the schematic printed on new oe relays, it's depicted as a straight line whereas the stock ones have the zigzag line printed on them.
I was able to find a relay that had the matching schematic, it was a gray relay not for the maf system, and I found it browsing high load relays for camaros online from auto stores. I never did buy it to compare tho...
I also depinned, cleaned, regreased the 3 relays. I dunno if it helped neccessarily but you will surely find the grease is nasty by now.
I was able to find a relay that had the matching schematic, it was a gray relay not for the maf system, and I found it browsing high load relays for camaros online from auto stores. I never did buy it to compare tho...
I also depinned, cleaned, regreased the 3 relays. I dunno if it helped neccessarily but you will surely find the grease is nasty by now.
#7
Senior Member
Re: Hard to start with new maf
Rockauto sells these replacement relays, as does many local car parts stores. I have several on hand in my parts stash. I've tested them to make sure they work. They are not too expensive.
On my firewall driver side there are 3 relays. Fuel pump, MAF power and MAF burnoff. Both MAF relays have been replaced a couple times. I'm original owner of the car and I think that fuel pump relay is the original. Still works.
On my firewall driver side there are 3 relays. Fuel pump, MAF power and MAF burnoff. Both MAF relays have been replaced a couple times. I'm original owner of the car and I think that fuel pump relay is the original. Still works.
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#8
Junior Member
Re: Hard to start with new maf
if you have a nice multimeter you should try putting a t-pin on the signal wire from the maf and testing while running. if I remember right the voltage is between 0-2.5v on that wire depending on how much air it thinks it needs to account for. mine would periodically jump to 2.5v and stick, which was not right for a car idling. even tho I have a basic multimeter that is very slow, it was bad enough to detect. it let me know that the maf was malfunctioning.
#9
Senior Member
Re: Hard to start with new maf
if you have a nice multimeter you should try putting a t-pin on the signal wire from the maf and testing while running. if I remember right the voltage is between 0-2.5v on that wire depending on how much air it thinks it needs to account for. mine would periodically jump to 2.5v and stick, which was not right for a car idling. even tho I have a basic multimeter that is very slow, it was bad enough to detect. it let me know that the maf was malfunctioning.
You bring up another good point is the response time of the DVM. Mine is very accurate but rather slow on the updates.
#11
Junior Member
Re: Hard to start with new maf
Huh, that's interesting, I never considered interference. I'll keep that in mind for future test endeavors. You all are a lot more pro than me doing road tests! I idled/reved it in in the driveway with the multimeter propped against the windshield, so the wire wasnt too long. Admittedly, it was a cheap, flimsy wire. If I knew how to pin where it goes into the ecu I would.
Do you have to remove the ecu to test? I know you have to be careful to avoid shorting.
Do you have to remove the ecu to test? I know you have to be careful to avoid shorting.
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